赵海根
, 杨胜天
Zhao Haigen, Yang Shengtian
中图分类号: P339
文献标识码: A
文章编号: 1000-0690（2017）07-1112-08
收稿日期: 2016-08-30
修回日期: 2016-12-14
网络出版日期: 2017-07-20
版权声明: 2017 《地理科学》编辑部 本文是开放获取期刊文献，在以下情况下可以自由使用：学术研究、学术交流、科研教学等，但不允许用于商业目的.
基金资助:
作者简介:
作者简介: 赵海根（1983-）,男,河北邯郸人,工程师,主要从事生态水文研究。E-mail:zhaohaigen1983@163.com
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摘要
分别利用分布式时变增益水文模型（DTVGM）和分布式耗水过程模型（DEPM）对延河流域延安水文站以上区域进行水文过程模拟,并应用拓展卡尔曼滤波(EKF)算法对2个模型的绿水(实际蒸散发)模拟结果进行同化处理,从而优化了研究区的绿水量并得出绿水的空间分布规律。结果表明：在整个模拟期,DTVGM的月尺度效率系数（NSCE）达到了0.83,水量平衡相对误差为-1.97%,模型能够较好地模拟研究区的水文过程;DEPM的水量平衡相对误差为-1.81%,能较好地模拟流域的水量平衡;DTVGM和DEPM模拟的流域2010年平均绿水量分别为378.52 mm和375.55 mm,空间分布格局相似。与站点观测值比较,DTVGM和DEPM模拟绿水的NSCE分别是0.76和0.59,DEPM的结果具有更多的空间变化信息。同化结果表明EKF算法能综合优化2个模型的模拟结果,同化后DTVGM模拟研究区的平均绿水量为376.34 mm,NSCE为0.78;同化后研究区绿水标准差为40.37 mm,比同化前增加了7.79 mm,绿水空间分布体现了更多的空间变化信息,同时,空间分布时格局也更加合理。
关键词：
Abstract
The accurate green water simulation is very important for the crop growth, agricultural drought monitoring, food security and rational allocation of water resources. Now, there are three methods which can be used to get greenwater: field observation, remote sensing calculation and hydrological model simulation. The field observation can not get the accurate simulation result of catchment green water at large scale because of complicated spatial heterogeneity; the remote sensing calculation method can only get the instantaneous simulation result at a large scale region. Compared to the two methods above, the hydrological model can get the continuous green water simulation results in large scale catchment. But, because hydrological models have different structures and characteristics, different simulation results can be got when inputting the same simulation data in the same region. In order to comprehensively utilize the simulation results of different hydrological models, the data assimilation method is a good choice. In this study, the Distributed Time Variant Gain Model(DTVGM) and Distributed Evapotranspiration Process Model(DEPM) were used to simulate the hydrological process in the catchment controlled by the Yan’an station in the Yanhe River Basin based on their structures and characteristics, and the Extended Kalman Filter(EKF) data assimilation algorithm was used to assimilate the green water (actual evapotranspiration) simulated by the two models to optimize the green water in the study area. The statistical indexes show that the simulation result of DTVGM is applicable to simulate the hydrological processes in this study area, the Nash-Sutcliffe coefficient(NSCE) is 0.83 and the relative water balance is -1.97% in the whole simulation period. The water balance relative index of DEPM is -1.81% in the whole simulation period, which shows that DEPM can model the water balance well at the study area.Besides, the simulation results show that the green water in 2010 simulated by the two models is 378.52 mm and 375.55 mm, respectively. There are not obvious difference for the mean simulation results of two models and the spatial distribution pattern are also similar, but there is more spatial variable information for result simulated by DEPM model than that of DTVGM. Compared to the observed green water, the NSCE of green water simulated by DTVGM and DEPM is respectively 0.76 and 0.59, but the spatial distribution of green water simulated by DEPM has more change information. Then, the green water simulation result of DEPM was used as “observed value” to assimilate the green water simulated by DTVGM based on the EKF data assimilation method in order to optimize the green water simulation result.The average green water simulated by DTVGM after data assimilation is 376.42 mm and the NSCE is 0.78 when comparing to the observed green water. The Standard Deviation(SD) for the green water simulation becomes 40.37 mm after assimilation, which is significantly increased by 7.79 mm than the original modeling results. The green water in spatial distribution shows more spatial change information and is more reasonable in this study area.
Keywords：
绿水是区域降水下渗到非饱和土壤层中进而垂向进入大气的不可见水[1,2],是区域水文循环的重要环节之一。绿水的准确获得对于区域的农作物的生长、农业旱情监测、粮食安全和水资源合理配置都有重要意义[3,4]。
目前,绿水量可以利用实验观测、遥感估算和水文模型模拟等途径得到。实验观测都是基于样地或者景观尺度,而对于大空间尺度区域,由于复杂的时空异质性的存在,实验观测很难准确反映出绿水的空间变化[3]。遥感数据能够提供大空间尺度的地表观测数据,且能够与地面观测数据相互配合,在区域蒸散发估算中具有其他手段不可比拟的优势[5,6]。但是,基于遥感数据估算绿水受到卫星过境时间的限制只能计算瞬时绿水,对要获取不同时间步长的绿水量具有一定的困难[7]。集成遥感数据的分布式水文模型能够较为细致地反映区域的时空异质性,获取较长时间步长的绿水,能较好地模拟区域绿水的时空格局变化[8,9]。
然而,不同水文模型具有不同的结构和参数,往往对相同驱动数据的绿水计算产生不同的结果[10,11],而数据同化为综合利用不同模型结果提供了一条新的途径[12]。数据同化可以将精度较高的结果集成到水文模型当中,从而不断对模型的状态和参数进行更新,继而提高物理模型模拟或预报的精度[13]。近年来,同化技术逐渐应用于水文模型建模的研究中[14,15],但同化流域尺度上不同模型绿水模拟结果的研究比较少。
本研究以延河流域延安水文站控制的集水区为例,应用2个耦合遥感数据的分布式水文模型模拟流域的水文过程,然后对2个模型绿水模拟结果进行同化,进而优化流域绿水量。研究结果可为流域水资源的管理、合理配置及其生态规划提供科学依据。
研究区位于黄河中游的多沙粗沙区(图1),是延安水文站控制的集水区,面积3 197.32 km2。研究区多年观测的平均径流量为0.71×108m3,多年观测的平均输沙量为0.72×107m3。研究区的土壤类型以黄绵土为主,其次为黑垆土、红胶土和淤土。研究区内植被类型包括森林、灌丛和草原,植物种类丰富,草地和农作物的面积占研究区总面积的80%以上。
图1 研究区地理位置及雨量站、水文站分布
Fig.1 Location of study area and distributions of rainfall station and hydrological station
本研究分别利用分布式时变增益模型（DTVGM）和分布式耗水过程模型（DEPM）模拟验证研究区2010年的绿水,然后对2个模型的模拟结果进行同化处理。以下简单介绍涉及到的模型和方法。
DTVGM采用水文循环机理与水文非线系统理论相结合的方法进行水文过程模拟,时变增益是模型的核心[16]。DTVGM 既有分布式水文概念性模拟的特征,同时具有水文系统分析适应能力强的优点,在中国的干旱、半干旱以及湿润地区多个流域的应用,证明模型能够在水文资料信息不完全或者有不确定性干扰条件的情况下获得比较好的分布式水文模拟效率[16~18]。DTVGM模型通过流域出口观测值对流域的产汇流水文过程进行校正和模拟。
以土壤-植被-大气之间的水分运动过程为建模基础,DEPM包括降水植被截留模块、土壤水运动模块和蒸散发模块[19]。模型既具有明确的物理学机制,又能耦合遥感数据,并将土壤水运动过程和降水、截留、蒸发等边界条件联动,实现耗水过程空间模拟。本模型应用具有物理机制的Richards方程模拟土壤水的一维垂向运动。通过土壤水运动模拟,计算时间节点末的土壤含水量。DEPM侧重流域计算单元垂直方向水文变化过程,而对流域水平汇流考虑不足。
对于DTVGM的径流模拟结果,为了同时考虑丰水、平水、枯水月份的模拟效果,本研究选取2010年偶数位月份的模拟径流进行参数率定,奇数位月份模拟径流用于参数验证[20]。纳什系数（NSCE)和水量平衡相对误差(WE)[18]被用来对模型的模拟结果进行评价。而DEPM 模型缺少汇流过程,所以采用水量平衡的方法对径流模拟结果进行分析评价。
本研究将中国气象数据共享网上的蒸散发大器皿观测潜在蒸散发乘以大水面蒸发折算系数、高程校正系数和陆面蒸散发量折算系数后得到近似的绿水“真值”,进而生成泰森多边形计算研究区面月尺度绿水“真值”来验证模拟实际蒸散总量[21]。具体转换方程如下：
式中,
本研究采用拓展性卡尔曼滤波（EntendedKalman Filter, EKF）[12,22]对DTVGM 和DEPM模拟结果进行同化处理。EKF是以线性最小方差估计理论为依据,以前一个时刻的估计值和当前时刻的观测值来更新对变量的估计,求出当前时刻的状态值。状态方程、量测方程、白噪声激励的统计特性和量测误差的统计特性是EKF运算过程中涉及到的4类信息[23]。EKF将非线性观测方程在滤波预测值时刻的滤波值展开成泰勒级数,略去二次以上项后得到的非线性系统的线性化模型,并取低次项逼近它们,得到扩展卡尔曼滤波的方程组[24]。
EKF运算所涉及到的方程如下：
状态方程：
测量方程：
状态预测方程：
X(k|k-1)的协方差：
状态卡尔曼增益矩阵：
状态估计值：
更新K状态下X(k|k)的协方差：
式中,X(k)是目标k时刻的状态向量,Φ(k,k-1)是系统的状态转移矩阵,W(k)是系统随机干扰向量,Z(k)是系统的观测向量,V(k)是系统的观测噪声向量,H(k)是观测矩阵。P(k,k-1)和P(k|k)分别是X(k,k-1)和X(k|k)对应的协方差矩阵,K 为卡尔曼增益。
DTVGM和DEPM各个子模块中涉及的参数及其获取方法见表1,模型参数包括气象参数和下垫面地表参数,其中下垫面地表参数可基于公用数据平台的遥感和GIS数据产品确定。
5~9月份的绿水验证的大器皿观测潜在蒸散发站点（53738,53740,53754和53845）数据是从中国气象数据共享网上下载。
表1 水文模型的地表参量及其获取方法
Table 1 Surface parameters and acquisition method of hydrological models
| 名称 | 单位 | 获取方法 | 数据源 |
|---|---|---|---|
| 降水量 | mm | 反距离加权插值 | 气象站点 |
| 日均气温 | ℃ | 反距离加权插值 | 气象站点 |
| 日均水汽压 | hPa | 反距离加权插值 | 气象站点 |
| 日照时数上 | h | 反距离加权插值 | 气象站点 |
| 高程 | m | 遥感产品 | Shuttle Radar Topography Mission |
| 叶面积指数 | 无量纲 | 遥感产品 | Moderate-resolution Imaging Spectroradiometer |
| 地表反照率 | % | 遥感产品 | Moderate-resolution Imaging Spectroradiometer |
| 土地覆被类型 | 无量纲 | 遥感解译 | Landsat TM |
| 土壤类型 | 无量纲 | 遥感产品 | Harmonized World Soil Database version |
1）DTVGM 模拟径流结果验证。DTVGM在校正期和验证期的纳什系数分别为0.84和0.41。根据Beskow等[25]的研究,当0.36< NSCE<0.75时,模型模拟的效果是可以接受的。图2显示了DTVGM模型在率定期和验证期模拟的延安站月径流线与实测径流线吻合较好,整个模拟期的效率系数为0.83,水量平衡相对误差分别为-1.97%,模拟精度达到要求。
图2 DTVGM模型2010年延安水文站模拟径流与实测径流对比
Fig.2 Comparison of monthly simulated and observed runoff for DTVGM at Yan’an hydrological station in 2010
图3虽然显示DTVGM对于峰值的模拟不是非常理想,但这种现象普遍存在于大量的研究之中[25~27]。Viola等[26]特别强调了准确获取能代表模拟时段的空间降雨数据是模型能否成功模拟峰值的关键。Notter等[27]认为以下几个理由可以解释模型模拟峰值不理想：① 研究区降雨的空间分布不能被降雨观测网络及时准确地获取;② 研究区一天中雨强处于不断变化之中甚至一天之内有多场降雨发生,而这些因素水文模型模拟都没有考虑。除此之外,研究区内降雨多以强降雨为主也加大了模型对于峰值模拟的难度。
2） DEPM模拟径流结果分析。DEPM首先进行植被截留的计算,植被截留量以蒸散发的形式返回大气。模型的核心是Richards土壤水的运动方程,通过节点土壤水的计算连接经验公式Ritchie分别计算土壤蒸发和植被蒸腾。由于模型不进行汇流,所以只对其水量平衡相对误差进行分析,水量平衡相对误差值为-1.81%,能较好地对流域水量平衡进行模拟。
由图3可以看出,DTVGM模拟的绿水量效率系数比DEPM模拟的结果高0.17,相关系数也比DEPM结果要好,这是由于DTVGM模拟结果是通过径流进行率定的结果。
图3 同化前DEPM 和DTVGM模型5~9月份月绿水量评价
Fig.3 Monthly green water evaluation simulated by DEPM and DTVGM between May and September in 2010 before data assimilation
2个模型对研究区2010年的绿水进行了模拟,DEPM计算的流域平均绿水量为375.55 mm,比DTVGM计算的结果量小2.97 mm。图4显示2个模型绿水模拟的空间分布,可以看出2个模型模拟的空间趋势一致,绿水量从研究区西北部向东南部递增。
图4 水文模型模拟研究区绿水空间分布
Fig.4 Distribution of green water simulated by distributed hydrological model
从图4a和4b的比较结果来看,DEPM模拟的绿水结果包含更多的空间变化信息,DTVGM的模拟值空间变化信息较少。这是因为流域水文模型汇流过程中易受到水库调节和水资源开采的影响[12],绿水的计算和水资源利用信息高度相关,而延河流域最近几年水资源开采非常严重,由于很难获得这些水利用信息,所以DTVGM在准确获取流域整体水文过程值的同时很难准确反映流域内绿水的空间分布特征,而DEPM只是进行一维的垂向计算不需要进行水平的汇流,所以流域内空间分布特征较好。因此,我们利用DEPM模拟的绿水结果作为“观测值”去同化DTVGM模拟的结果以期待达到优化绿水计算结果的目的。
表2总结了2个模型的模拟结果和同化前后绿水在流域尺度上平均值和标准差(Standard Deviation, SD)的对比。通过表2可以看出,DTVGM模型同化前2个指标平均值和标准差分别为378.52 mm和32.58 mm,同化后这2个指标的对应值分别为376.34 mm和40.37 mm。与同化前相比较,DTVGM同化后的平均值变化幅度不大,减少了2.18 mm,说明同化并没有对研究区绿水总量进行过大影响,SD同化后增大了7.79 mm,表明同化后的结果具有更多的差异性。图5显示同化后DTVGM模拟的绿水量和观测值的NSCE为0.78,比同化前DTVGM模拟的绿水量有少量提高。图6显示了DTVGM同化前后绿水的空间分布格局变化图。
表2 DEPM和DTVGM模拟绿水同化前后平均值、标准差和均方根误差的对比（mm）
Table 2 Comparisons of average value, SD and RMSE for green water simulated by DEPM and before and after assimilating green water simulated by DTVGM (mm)
| 时间 | DEPM | DTVGM同化前 | DTVGM同化后 | |||||
|---|---|---|---|---|---|---|---|---|
| 平均值 | 标准差 | 平均值 | 标准差 | 平均值 | 标准差 | |||
| 2010年 | 375.55 | 47.20 | 378.52 | 32.58 | 376.34 | 40.37 | ||
图5 同化后DTVGM模型5~9月绿水量评价
Fig.5 Monthly green water evaluation simulated by DTVGM between May and September in 2010 after data assimilation
对比图6a和6b可以看出,同化后的结果比同化前包含了更多的空间变化信息,研究区上游部分区域绿水量有所减小,从349.10~382.00 mm区间变化到283.01~349.00 mm区间;而研究区下游部分区域的绿水量有所增加,主要从382.01~415.00 mm区间增加到448.01~547.00 mm区间。
图6 DTVGM同化前后绿水空间分布
Fig.6 Distribution of green water simulated by DTVGM before and after assimilation
DTVGM和DEPM对研究区2010年绿水的模拟值分别是378.52 mm和375.55 mm。赵静等[28]运用流域估算模型对黄河中游区域1970~2000年之间进行了实际蒸散发的模拟。除了极少数的极值外,文献中延河流域的多年平均实际蒸散发与本文的研究结果相符。可见,DTVGM和DEPM可以进行大空间尺度的绿水模拟估算,结果精度可靠。
本研究运用耦合遥感数据的DTVGM和DEPM对延河流域延安水文站控制区域绿水进行模拟,并对2个模型模拟结果进行了同化处理,得到结论如下：
1） DTVGM能较好地模拟研究区的水文过程,月尺度径流模拟和实测值的NSCE为0.83,WE为1.93%;对于DEPM来说,水量平衡相对误差为-1.81%,模型能较好地模拟流域的水量平衡过程;
2） 同化前DTVGM和DEPM模拟的研究区2010年平均绿水量分别为378.52 mm和375.55 mm,空间分布趋势相似。与绿水站点观测值相比较,DTVGM和DEPM模拟的绿水NSCE值分别为0.76和0.59,但是DEPM模拟的结果具有更多的空间变化信息;
3） EFK方法的同化处理提高了DTVGM的绿水空间格局模拟效果,同化后标准差比同化前增加了7.79 mm,体现了更多的空间变化信息;
4） 同化结果较好地反映了研究区2010年的绿水时空变化。同化后研究区的绿水量平均值为376.34 mm,范围在256.07~531.05 mm之间,与站点观测值相比较,NSCE值有略微的提高。
The authors have declared that no competing interests exist.
| [1] |
流域绿水研究的关键科学问题 [J].
阐述了开展流域绿水研究的重要意义，分析了流域绿水研究的关键科学问题：①绿水量的测算方法与尺度转换;②流域绿水流的形成、转化及其生态水文响应机理;③流域绿水资源评价与管理。指出流域水资源评价与管理要以降水为基本水资源，综合考虑蓝水和绿水两部分，协调流域上、中、下游生态、生产和生活用水，充分开发利用非生产性绿水资源，平衡自然生态和人类用水。
Key scientific issues for green water research in the watershed.
阐述了开展流域绿水研究的重要意义，分析了流域绿水研究的关键科学问题：①绿水量的测算方法与尺度转换;②流域绿水流的形成、转化及其生态水文响应机理;③流域绿水资源评价与管理。指出流域水资源评价与管理要以降水为基本水资源，综合考虑蓝水和绿水两部分，协调流域上、中、下游生态、生产和生活用水，充分开发利用非生产性绿水资源，平衡自然生态和人类用水。
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| [2] |
气候变化和人类活动对渭河流域蓝水绿水影响研究 [J].
以渭河流域为研究对象，探讨了1980～2009年气候变化和人类活动对蓝绿水资源的影响。结果表明：①研究时段内，在气候变化和人类活动的共同影响下，蓝水流、绿水流和绿水储量分别下降了23．56mm／a、39．41mm／a和17．98mm／a，中北部的蓝水流和绿水储量呈现增加的趋势，流域上游地区的绿水流呈现下降趋势。②归因分析表明，蓝水流、绿水流和绿水储量在气候变化驱动下分别下降了13．17mm／a、44．99mm／a和22．79mm／a；土地利用／覆盖变化则导致蓝水流和绿水流分别减少0．42mm／a和0．37mm／a，绿水储量增加了0．79mmfa；而农业灌溉使蓝水流减少了9．97mm／a，绿水流和绿水储量分别增加了5．95mm／a和4．02mm／a。③气候变化导致研究区东南部绿水系数呈现增加趋势，而泾河流域绿水系数呈现减小趋势。同时，土地利用／覆盖变化使得东南部的一些子流域绿水系数呈减小的趋势，而在加入农业灌溉情景后，平原地区灌区绿水系数呈明显的上升趋势。
Impact of human activities and climate variability on green and blue water resources in the weihe river basin of northwest China.
以渭河流域为研究对象，探讨了1980～2009年气候变化和人类活动对蓝绿水资源的影响。结果表明：①研究时段内，在气候变化和人类活动的共同影响下，蓝水流、绿水流和绿水储量分别下降了23．56mm／a、39．41mm／a和17．98mm／a，中北部的蓝水流和绿水储量呈现增加的趋势，流域上游地区的绿水流呈现下降趋势。②归因分析表明，蓝水流、绿水流和绿水储量在气候变化驱动下分别下降了13．17mm／a、44．99mm／a和22．79mm／a；土地利用／覆盖变化则导致蓝水流和绿水流分别减少0．42mm／a和0．37mm／a，绿水储量增加了0．79mmfa；而农业灌溉使蓝水流减少了9．97mm／a，绿水流和绿水储量分别增加了5．95mm／a和4．02mm／a。③气候变化导致研究区东南部绿水系数呈现增加趋势，而泾河流域绿水系数呈现减小趋势。同时，土地利用／覆盖变化使得东南部的一些子流域绿水系数呈减小的趋势，而在加入农业灌溉情景后，平原地区灌区绿水系数呈明显的上升趋势。
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| [3] |
泾河上游流域实际蒸散量及其各组分的估算 [J].Estimation of actual evapotranspiration and its component in the upstream of Jinghe Basin. |
| [4] |
用SWAT模拟土地利用对绿水蓝水的影响:以晋江西溪流域为例 [J].
应用SWAT模型,研究了晋江西溪流域土地利用/覆被变化(LUCC)对绿水与蓝水资源时空分布的影响。结果表明,土地利用变化导致的西溪流域绿水资源从1970年代的年均625.34 mm减少到2001年的618.5 mm,年绿水总量平均减少了6.48 mm;蓝水资源从1970年代的年均1 019.44 mm增加到2001年的1 026.49 mm,年蓝水总量平均增加了7.05 mm。土地利用变化造成年内12个月份的绿水都有所减少,蓝水都有所增加,其中处于汛期的6-9月蓝水增加量较大。由于流域上游几个亚流域的林地耕地面积之和大幅减少等原因,绿水的减少与蓝水的增加主要集中于流域上中游的几个亚流域。
Simulation of the effect of land use/cover change on green and blue water resource in Xixi watershed of the Jinjiang Basin with SWAT model.
应用SWAT模型,研究了晋江西溪流域土地利用/覆被变化(LUCC)对绿水与蓝水资源时空分布的影响。结果表明,土地利用变化导致的西溪流域绿水资源从1970年代的年均625.34 mm减少到2001年的618.5 mm,年绿水总量平均减少了6.48 mm;蓝水资源从1970年代的年均1 019.44 mm增加到2001年的1 026.49 mm,年蓝水总量平均增加了7.05 mm。土地利用变化造成年内12个月份的绿水都有所减少,蓝水都有所增加,其中处于汛期的6-9月蓝水增加量较大。由于流域上游几个亚流域的林地耕地面积之和大幅减少等原因,绿水的减少与蓝水的增加主要集中于流域上中游的几个亚流域。
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| [5] |
Application of remote sensing-based two-source energy balance model for mapping field surface fluxes with composite and component surface temperatures [J].https://doi.org/10.1016/j.agrformet.2016.01.005 URL [本文引用: 1] 摘要
Operational application of a remote sensing-based two source energy balance model (TSEB) to estimate evaportranspiration ( ET ) and the components evaporation ( E ), transpiration ( T ) at a range of space and time scales is very useful for managing water resources in arid and semiarid watersheds. The TSEB model uses composite land surface temperature as input and applies a simplified Priestley鈥揟aylor formulation to partition this temperature into soil and vegetation component temperatures and then computes subsequent component energy fluxes. The remote sensing-based TSEB model using component temperatures of the soil and canopy has not been adequately evaluated due to a dearth of reliable observations. In this study, soil and vegetation component temperatures partitioned from visible and near infrared and thermal remote sensing data supplied by advanced scanning thermal emission and reflection radiometer (ASTER) are applied as model inputs (TSEB CT ) to assess and refine the subsequent component energy fluxes estimation in TSEB scheme under heterogeneous land surface conditions in an advective environment. The model outputs including sensible heat flux ( H ), latent heat flux ( LE ), component LE from soil and canopy from the TSEB CT and original model (TSEB PT ) are compared with ground measurements from eddy covariance (EC) and larger aperture scintillometers (LAS) technique, and stable isotopic method. Both model versions yield errors of about 10% with LE observations. However, the TSEB CT model output of H and LE are in closer agreement with the observations and is found to be generally more robust in component flux estimation compared to the TSEB PT using the ASTER data in this heterogeneous advective environment. Thus given accurate soil and canopy temperatures, TSEB CT may provide more reliable estimates of plant water use and values of water use efficiency at large scales for water resource management in arid and semiarid landscapes.
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| [6] |
遥感蒸散发模型研究进展综述 [J].A review on evapotranspiration estimation models using remotely sensed data. |
| [7] |
分布式水文模型结合遥感研究地表蒸散发 [J].https://doi.org/10.3969/j.issn.1000-0690.2007.03.011 URL [本文引用: 1] 摘要
地表蒸散发是研究土壤-植被-大气系统水热平衡的关键因子。用改进的DHSVM分布式水文模型对汉江上游子午河流域蒸散发进行模拟。根据流域特点,主要进行TM遥感数据的大气校正和几何校正,在此基础上得到叶面积指数和土地覆盖等地表参数;再利用GIS技术基于DEM求出坡度、坡向和地形指数等因子。分析了蒸散发时空分布特征,表明日尺度蒸散发空间分布差异较大。初步验证了结果,表明模型在中国典型湿润区小流域取得较好效果。
Simulation of land surface evapotraspiration using distributed hydrological model,remote sensing and GIS technology. https://doi.org/10.3969/j.issn.1000-0690.2007.03.011 URL [本文引用: 1] 摘要
地表蒸散发是研究土壤-植被-大气系统水热平衡的关键因子。用改进的DHSVM分布式水文模型对汉江上游子午河流域蒸散发进行模拟。根据流域特点,主要进行TM遥感数据的大气校正和几何校正,在此基础上得到叶面积指数和土地覆盖等地表参数;再利用GIS技术基于DEM求出坡度、坡向和地形指数等因子。分析了蒸散发时空分布特征,表明日尺度蒸散发空间分布差异较大。初步验证了结果,表明模型在中国典型湿润区小流域取得较好效果。
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| [8] |
Impacts of land use change and climate variability on green and blue water resources in the Weihe River Basin of northwest China [J].https://doi.org/10.1016/j.catena.2015.09.018 URL [本文引用: 1] 摘要
Farmland area decreased by 1.4% and woodland, grassland, and construction land area increased by 0.6%, 0.2%, and 0.6%, respectively. The combined impact of land use change, agricultural irrigation expansion and climate variation decreased the blue water flow, green water flow, and green water storage by 21.6202mm02year 61021 , 35.0102mm02year 61021 and 28.0702mm02year 61021 , respectively. Climate variability decreased the blue/green water flow and green water storage, land use change decreased the blue water and green water flow while it increased the green water storage, irrigation expansion decreased the blue water flow while it increased the green water flow/storage. The spatial distribution showed an uneven change in the Weihe River Basin. Together, we suggested that the variability of water resources availability in the Weihe River Basin was mainly attributed to climate variability, while land use change plays a key role in the sub-basins which experienced dramatic changes in land use.
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| [9] |
Data assimilation of satellite-based actual evapotranspiration in a distributed hydrological model of a controlled water system [J].https://doi.org/10.1016/j.jag.2016.12.015 URL [本文引用: 1] 摘要
Advances in earth observation (EO) and spatially distributed hydrological modelling provide an opportunity to improve modelling of controlled water systems. In a controlled water system human interference is high, which may lead to incorrect parameterisation in the model calibration phase. This paper analyses whether assimilation of EO actual evapotranspiration (ETa) data can improve discharge simulation with a spatially distributed hydrological model of a controlled water system. The EO ETa estimates are in the form of eight-day ETa composite maps derived from Terra/MODIS images using the ITA-MyWater algorithm. This algorithm is based on the surface energy balance method and is calibrated for this research for a low-lying reclamation area with a heavily controlled water system: the Rijnland area in the Netherlands. Data assimilation (DA) with the particle filter method is applied to assimilate the ETa maps into a spatially distributed hydrological model. The hydrological model and DA framework are applied using the open source software SIMGRO and PCRaster-Python respectively. The analysis is done for a period between July and October 2013 in which a high discharge peak followed a long dry-spell. The assimilation of EO ETa resulted in local differences in modelled ETa compared to simulation without data assimilation, while the area average ETa remained almost the same. The modelled cumulative discharge graphs, with and without DA, showed distinctive differences with the simulation, with DA better matching the measured cumulative discharge. The bias of simulated cumulative discharge to the observed data reduced from 14% to 4% when using DA of EO ETa. These results showed that assimilating EO ETa may not only be effective in the more common applications of soil moisture and crop-growth modelling, but also for improving discharge modelling of controlled water systems.
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| [10] |
水均衡法验证蒸散量计算的可靠性——以张掖盆地为例 [J].https://doi.org/10.3969/j.issn.1000-8527.2008.02.018 URL Magsci [本文引用: 1] 摘要 蒸散量的计算方法有很多种，表面能量平衡系统（SEBS）是近年来应用较为广泛的计算蒸散量的方法之一。SEBS是应用卫星对地观测的可见光、近红外和热红外波段资料，结合实测气象数据或大气模式输出数据，根据表面能量平衡原理估算不同尺度的地表大气湍流通量，从而估算地表相对蒸散的一种方法。将水文数据与遥感数据相结合，运用SEBS方法对张掖盆地的区域蒸散量进行了估算，并在水均衡原理的基础上，对蒸散量计算结果的准确性进行了验证。结果表明：SEBS方法计算的蒸散量与水均衡法计算出的蒸散量结果吻合较好，从而验证了SEBS方法计算盆地蒸散量的准确性。 Accuracy verification of evapotranspiration result using hydrological budget Method-A case study of the zhangye basin. https://doi.org/10.3969/j.issn.1000-8527.2008.02.018 URL Magsci [本文引用: 1] 摘要 蒸散量的计算方法有很多种，表面能量平衡系统（SEBS）是近年来应用较为广泛的计算蒸散量的方法之一。SEBS是应用卫星对地观测的可见光、近红外和热红外波段资料，结合实测气象数据或大气模式输出数据，根据表面能量平衡原理估算不同尺度的地表大气湍流通量，从而估算地表相对蒸散的一种方法。将水文数据与遥感数据相结合，运用SEBS方法对张掖盆地的区域蒸散量进行了估算，并在水均衡原理的基础上，对蒸散量计算结果的准确性进行了验证。结果表明：SEBS方法计算的蒸散量与水均衡法计算出的蒸散量结果吻合较好，从而验证了SEBS方法计算盆地蒸散量的准确性。 |
| [11] |
Quantifying global evapotranspiration from remote sensing: Estimates, trends and uncertainties for terrestrial hydrology[D]. |
| [12] |
Integrating remote sensing information into a distributed hydrological model for improving water budget predictions in large-scale basins through data assimilation [J].https://doi.org/10.3390/s8074441 URL PMID: 3697185 [本文引用: 3] 摘要
This paper investigates whether remote sensing evapotranspiration estimates can be integrated by means of data assimilation into a distributed hydrological model for improving the predictions of spatial water distribution over a large river basin with an area of 317,800 km2. A series of available MODIS satellite images over the Haihe River basin in China are used for the year 2005. Evapotranspiration is retrieved from these 1脙茠脗鈥1 km resolution images using the SEBS (Surface Energy Balance System) algorithm. The physically-based distributed model WEP-L (Water and Energy transfer Process in Large river basins) is used to compute the water balance of the Haihe River basin in the same year. Comparison between model-derived and remote sensing retrieval basin-averaged evapotranspiration estimates shows a good piecewise linear relationship, but their spatial distribution within the Haihe basin is different. The remote sensing derived evapotranspiration shows variability at finer scales. An extended Kalman filter (EKF) data assimilation algorithm, suitable for non-linear problems, is used. Assimilation results indicate that remote sensing observations have a potentially important role in providing spatial information to the assimilation system for the spatially optical hydrological parameterization of the model. This is especially important for large basins, such as the Haihe River basin in this study. Combining and integrating the capabilities of and information from model simulation and remote sensing techniques may provide the best spatial and temporal characteristics for hydrological states/fluxes, and would be both appealing and necessary for improving our knowledge of fundamental hydrological processes and for addressing important water resource management problems.
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| [13] |
Data assimilation for distributed hydrological catchment modeling via ensemble Kalmanfilter [J].https://doi.org/10.1016/j.advwatres.2010.03.012 URL [本文引用: 1] 摘要
Catchment scale hydrological models are critical decision support tools for water resources management and environment remediation. However, the reliability of hydrological models is inevitably affected by limited measurements and imperfect models. Data assimilation techniques combine complementary information from measurements and models to enhance the model reliability and reduce predictive uncertainties. As a sequential data assimilation technique, the ensemble Kalman filter (EnKF) has been extensively studied in the earth sciences for assimilating in-situ measurements and remote sensing data. Although the EnKF has been demonstrated in land surface data assimilations, there are no systematic studies to investigate its performance in distributed modeling with high dimensional states and parameters. In this paper, we present an assessment on the EnKF with state augmentation for combined state-parameter estimation on the basis of a physical-based hydrological model, Soil and Water Assessment Tool (SWAT). Through synthetic simulation experiments, the capability of the EnKF is demonstrated by assimilating the runoff and other measurements, and its sensitivities are analyzed with respect to the error specification, the initial realization and the ensemble size. It is found that the EnKF provides an efficient approach for obtaining a set of acceptable model parameters and satisfactory runoff, soil water content and evapotranspiration estimations. The EnKF performance could be improved after augmenting with other complementary data, such as soil water content and evapotranspiration from remote sensing retrieval. Sensitivity studies demonstrate the importance of consistent error specification and the potential with small ensemble size in the data assimilation system.
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| [14] |
基于水文模型的蒸散发数据同化实验研究 [J].https://doi.org/10.11867/j.issn.1001-8166.2014.09.1075 Magsci [本文引用: 1] 摘要
流域蒸散发定量估算一直是水科学领域的研究前沿,水文模型和遥感反演是当前估算区域蒸散发的常用手段。研究通过数据同化,集成水文模型和遥感模型的优势,耦合遥感蒸散发到水文模型中以实现多源数据下的蒸散发数据同化。选择北京市沙河流域为研究区,分布式时变增益水文模型作为模型算子,基于集合卡尔曼滤波同化算法,利用双层遥感模型模拟的蒸散发同化水文模型,并基于地面通量站观测的日蒸散发进行验证。结果表明,同化结果与观测数据相比平均绝对百分比误差较同化前减少,精度进一步提升,且当遥感观测输入频繁时精度改善明显。研究证明基于水文模型的蒸散发数据同化系统,是一种可实现输出精度更高和时序连续的区域蒸散发的新型模式。该成果将进一步丰富创新蒸散发估算的学科内容,为准确理解区域水循环规律提供科学依据。
A case study of evapotranspiration data assimilation based on hydrological model. https://doi.org/10.11867/j.issn.1001-8166.2014.09.1075 Magsci [本文引用: 1] 摘要
流域蒸散发定量估算一直是水科学领域的研究前沿,水文模型和遥感反演是当前估算区域蒸散发的常用手段。研究通过数据同化,集成水文模型和遥感模型的优势,耦合遥感蒸散发到水文模型中以实现多源数据下的蒸散发数据同化。选择北京市沙河流域为研究区,分布式时变增益水文模型作为模型算子,基于集合卡尔曼滤波同化算法,利用双层遥感模型模拟的蒸散发同化水文模型,并基于地面通量站观测的日蒸散发进行验证。结果表明,同化结果与观测数据相比平均绝对百分比误差较同化前减少,精度进一步提升,且当遥感观测输入频繁时精度改善明显。研究证明基于水文模型的蒸散发数据同化系统,是一种可实现输出精度更高和时序连续的区域蒸散发的新型模式。该成果将进一步丰富创新蒸散发估算的学科内容,为准确理解区域水循环规律提供科学依据。
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| [15] |
Hydrological data assimilation with the Ensemble Square-Root-Filter: Use of streamflow observations to update model states for real-time flash flood forecasting [J].https://doi.org/10.1016/j.advwatres.2013.06.010 URL [本文引用: 1] 摘要
The objective of the study is to evaluate the potential of a data assimilation system for real-time flash flood forecasting over small watersheds by updating model states. To this end, the Ensemble Square-Root-Filter (EnSRF) based on the Ensemble Kalman Filter (EnKF) technique was coupled to a widely used conceptual rainfall-runoff model called HyMOD. Two small watersheds susceptible to flash flooding from America and China were selected in this study. The modeling and observational errors were considered in the framework of data assimilation, followed by an ensemble size sensitivity experiment. Once the appropriate model error and ensemble size was determined, a simulation study focused on the performance of a data assimilation system, based on the correlation between streamflow observation and model states, was conducted. The EnSRF method was implemented within HyMOD and results for flash flood forecasting were analyzed, where the calibrated streamflow simulation without state updating was treated as the benchmark or nature run. Results for twenty-four flash-flood events in total from the two watersheds indicated that the data assimilation approach effectively improved the predictions of peak flows and the hydrographs in general. This study demonstrated the benefit and efficiency of implementing data assimilation into a hydrological model to improve flash flood forecasting over small, instrumented basins with potential application to real-time alert systems.
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| [16] |
Development of distributed time-variant gain model for nonlinear hydrological systems [J].https://doi.org/10.1360/03yd0183 URL [本文引用: 2] 摘要
In this paper, a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach. Two models, i.e. the time-variant gain model (TVGM) and the distributed time-variant gain model (DTVGM) that are built on the platform of Digital Elevation Model (DEM), Remote Sensing (RS) and Unit Hydrological Process were proposed. The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern China and the Chaobai River basin located in the semihumid region of northern China. The results indicate that, in addition to the classic dynamic differential approach to describe nonlinear processes in hydrological systems, it is possible to study such complex processes through the proposed systematic approach to identify prominent hydrological relations. The DTVGM, coupling the advantages of both nonlinear and distributed hydrological models, can simulate variant hydrological processes under different environment conditions. Satisfactory results were obtained in forecasting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation.
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| [17] |
A distributed hydrological model driven by Multi-Source spatial data and its application in the Ili river basin of central Asia [J].https://doi.org/10.1007/s11269-014-0641-z URL 摘要
Hydrological simulation in ungauged regions is a popular topic in water resource and environmental research, and is also an important part of the international research initiative Predictions in Ungauged Basins (PUB). In this study, a multi-spatial data-based DTVGM (MS-DTVGM), combining multi-source spatial data (MS-spatial data) with the Distributed Time-Variant Gain Model (DTVGM), was built in order to reduce dependence on conventional observation, and was applied to the Ili River basin where traditional data sets are scarce. Because it utilizes MS-spatial data to measure precipitation, potential evapotranspiration, air temperature, vegetation parameters, and soil parameters, the model is driven purely by data from common platforms, thus overcoming the disadvantage of the large amounts of data typically required for distributed hydrological models. The inputs and simulation results were calibrated and validated using station or field observations. The results indicate that: 1) the MS-DTVGM is feasible in the Ili River basin; all model inputs can be acquired from multi-source spatial data and the key parameters are accurate; 2) the MS-DTVGM has good performance on a monthly time scale, and its simulation results can be used for a longer time-scale water resource analysis; and (3) daily runoff generation correlated strongly with snowmelt, the R 2 is about 0.69 indicating that the latter is an important contributor to water resources and suggesting that a snowmelt module is indispensable this area. The potential of distributed models for hydrological simulation in data-scarce regions using MS-spatial data was clearly demonstrated.
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| [18] |
Evaluating the suitability of TRMM satellite rainfall data for hydrological simulation using a distributed hydrological model in the Weihe River catchment in China [J].https://doi.org/10.1007/s11442-015-1161-3 URL [本文引用: 2] 摘要
The objective of this study is to quantitatively evaluate Tropical Rainfall Measuring Mission(TRMM) data with rain gauge data and further to use this TRMM data to drive a Distributed Time-Variant Gain Model(DTVGM) to perform hydrological simulations in the semi-humid Weihe River catchment in China.Before the simulations,a comparison with a10-year(2001-2010)daily rain gauge data set reveals that,at daily time step,TRMM rainfall data are better at capturing rain occurrence and mean values than rainfall extremes.On a monthly time scale,good linear relationships between TRMM and rain gauge rainfall data are found,with determination coefficients R~2 varying between 0.78 and 0.89 for the individual stations.Subsequent simulation results of seven years(2001-2007)of data on daily hydrological processes confirm that the DTVGM when calibrated by rain gauge data performs better than when calibrated by TRMM data,but the performance of the simulation driven by TRMM data is better than that driven by gauge data on a monthly time scale.The results thus suggest that TRMM rainfall data are more suitable for monthly streamflow simulation in the study area,and that,when the effects of recalibration and the results for water balance components are also taken into account,the TRMM 3B42-V7 product has the potential to perform well in similar basins.
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| [19] |
黄河中游典型流域植被耗水过程定量模拟研究[D] .Simulationof vegetation evapotranspiration procession in typical watersheds in the middle reach of the Yellow River. |
| [20] |
黄河流域黄土高原典型支流径流锐减成因定量研究[D] .Quantitative diagnose on sharpreduction of discharge in typical tributaries of the Yellow River in the Loess Plateau. |
| [21] |
黄河中游植被恢复对蒸散变化的影响分析[D] .A distributed modeling approach to analysis the impact of revegetation on the evapotranspiration change in the middle reaches of the Yellow River Basin. |
| [22] |
拓展卡尔曼滤波算法在目标跟踪中的改进及应用 [J].Improvement and application of extended kalman filter algorithm in target tracking. |
| [23] |
一种抑制拓展卡尔曼滤波的发散方法 [J].https://doi.org/10.3969/j.issn.1673-9728.2005.02.157 URL [本文引用: 1] 摘要
针对扩展卡尔曼滤波在Sandia惯性地形辅助导航(SITAN)系统中的发散问题进行分析,指出关键原因所在,并据此提出采用"冻结"增益矩阵和对增益矩阵加权相结合的扩展卡尔曼滤波方法,对该导航系统进行修正.仿真结果表明,此方法能够有效地抑制发散.
A method of preventing divergence of EKF. Journal of Projectiles, Rockets, https://doi.org/10.3969/j.issn.1673-9728.2005.02.157 URL [本文引用: 1] 摘要
针对扩展卡尔曼滤波在Sandia惯性地形辅助导航(SITAN)系统中的发散问题进行分析,指出关键原因所在,并据此提出采用"冻结"增益矩阵和对增益矩阵加权相结合的扩展卡尔曼滤波方法,对该导航系统进行修正.仿真结果表明,此方法能够有效地抑制发散.
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| [24] |
扩展卡尔曼滤波在目标跟踪中的应用研究 [J].https://doi.org/10.3969/j.issn.1009-2552.2013.10.025 URL [本文引用: 1] 摘要
扩展卡尔曼滤波在非平稳矢量信号和噪声环境下具有广泛的应用,针对机动目标运动模型的特点,采用基于扩展卡尔曼滤波的算法对运动目标进行跟踪处理,该算法首先建立了运动目标的状态模型和观测模型,然后对观测数据进行滤波和误差估计处理,最后通过计算机的蒙特卡洛仿真得到了滤波轨迹和运动目标的距离和角度误差,仿真结果表明,扩展卡尔曼滤波算法具有很好的目标跟踪性能.
https://doi.org/10.3969/j.issn.1009-2552.2013.10.025 URL [本文引用: 1] 摘要
扩展卡尔曼滤波在非平稳矢量信号和噪声环境下具有广泛的应用,针对机动目标运动模型的特点,采用基于扩展卡尔曼滤波的算法对运动目标进行跟踪处理,该算法首先建立了运动目标的状态模型和观测模型,然后对观测数据进行滤波和误差估计处理,最后通过计算机的蒙特卡洛仿真得到了滤波轨迹和运动目标的距离和角度误差,仿真结果表明,扩展卡尔曼滤波算法具有很好的目标跟踪性能.
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| [25] |
Performance of a distributed semi-conceptual hydrological model under tropicalwatershed conditions [J].https://doi.org/10.1016/j.catena.2011.03.010 URL [本文引用: 2] 摘要
Conceptual rainfall-runoff models at the watershed scale are useful tools for assisting in managing and planning water resources, making it possible to estimate streamflow and to predict hydrologic impacts due to land-use changes. The objective of this study was to calibrate and to validate the LAvras Simulation of Hydrology (LASH Model) (Beskow, 2009) in a Brazilian Tropical Watershed for daily streamflow. LASH is a continuous, distributed, semi-physically based model for simulation of different hydrologic components on a daily basis. The Shuffled Complex Evolution (SCE-UA) global search method was used with the LASH model in order to optimize model parameters that were found to be the most sensitive or not directly measurable. The LASH model was calibrated over a 2-year period, thereafter, the parameters obtained through the calibration were kept constant for the validation step using a different period of time from that analyzed during the calibration. The Nash–Sutcliffe coefficient (C) values found were 0.820 and 0.764 during calibration and validation, respectively, whereas, the C (log Q) values equal to 0.821 and 0.770 were obtained for the same periods. The SCE-UA method was found to be an efficient algorithm for searching ‘optimal’ model parameter values. It was possible to conclude that the model has a great potential for being applied in generating the long-term streamflow as well as flow-duration curves. Therefore, the model can reliably be applied under tropical conditions of this medium-sized watershed or other similar watersheds, thus making it useful to plan the sustainable development of similar tropical and subtropical watersheds.Research Highlights? The model can be applied to regions with scarcity of data. ? Only a few calibration parameters are necessary to use the LASH model. ? The SCE-UA method was efficient for finding ‘optimal’ parameter values. ? The LASH model predicted stream flows adequately in a medium-sized watershed.
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| [26] |
Modelagemhidrológicanabaciahidrográfica do Rio Aiuruoca,MG [J].https://doi.org/10.1590/S1415-43662009000500011 URL [本文引用: 1] |
| [27] |
Impacts of environmental change on water resources in the Mt.Kenya region [J].https://doi.org/10.1016/j.jhydrol.2007.06.022 URL [本文引用: 2] 摘要
Water resources are becoming increasingly scarce in the Mt. Kenya region. Land use and climate change may pose additional challenges to water management in the future. In order to assess the impacts of environmental change, the NRM3 Streamflow Model, a simple, semi-distributed, grid-based water balance model, is evaluated as a tool for discharge prediction in six meso-scale catchments on the western slopes of Mt. Kenya, and used to analyse the impact of land use and climate change scenarios on water resources. The calibration and validation results show an acceptable performance of the NRM3 Streamflow Model in simulating discharge. Input data represent the main limitation. Rainfall patterns in the mountainous catchments are very heterogeneous and difficult to capture with the monitoring network. River water abstractions make up 80鈥100% of naturalized dry season discharge, but amounts can only be approximately estimated. Under the scenarios of land use and climate change examined, the total amount as well as the variability of discharge will increase: Conversion of the forest area to crop- or grassland will increase annual runoff by 11% or 59%, respectively, by mainly increasing flood flows and, under cropland, slightly reducing low flows. Climate change as projected by the IPCC Task Group on Scenarios for Impact Assessment [IPCC-TCGIA, 1999. Guidelines in the use of data for climate impact and adaptation assessment. Version 1. Prepared by Carter, T.R., Hulme, M.., Lal, M., Intergovernmental Panel on Climate Change, Task Group on Scenarios for Climate Impact Assessment.] will result in an increase of annual runoff by 26%, with a severe increase in flood flows, and a reduction of the lowest flows to about a tenth of the current value.
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| [28] |
黄河中游河口-龙门区间陆面年蒸散量估 [J].Regional evapotranspiration estimation in Hekou-Longmen section of the Middle Reaches of the Yellow River. |
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