Ecological water demand of natural vegetation in the lower Tarim River

We have appraised the relationships between soil moisture, groundwater depth, and plant species diversity in the lower reaches of the Tarim River in western China, by analyzing field data from 25 monitoring wells across eight study sites and 25 permanent vegetation survey plots. It is noted that groundwater depth, soil moisture and plant species diversity are closely related. It has been proven that the critical phreatic water depth is five meters in the lower reaches of the Tarim River. We acquired the mean phreatic evaporation of different groundwater levels every month by averaging the two results of phreatic evaporation using the Qunk and Averyanov formulas. Based on different vegetation types and acreage with different groundwater depth, the total ecological water demand （EWD） of natural vegetation in 2005 was 2.4×10^8 m^3 in the lower reaches of the Tarim River. Analyzing the monthly EWD, we found that the EWD in the growth season （from April to September） is 81% of the year＇s total EWD. The EWD in May, June and July was 47% of the year＇s total EWD, which indicates the best time for dispensing artificial water. This research aims at realizing the sustainable development of water resources and provides a scientific basis for water resource management and sound collocation of the Tarim River Basin.

Changes in groundwater levels and the response of natural vegetation to transfer of water to the lower reaches of the Tarim River

Restoration and reconstruction of the degraded Tarim River ecosystem is an important challenge. A goal of an ecological water conveyance project is to protect and restore the natural vegetation in the lower reaches of Tadm River by transferring water from Bosten Lake, through the river channel, to the lower reaches. This study describes the changes in groundwater depth during the water transfer and the respondence of riparian vegetation to alterations in groundwater levels. The results indicate that groundwater depth along the Tarim River channel has a significant spatial-temporal component. Groundwater levels closest to the river channel show the most immediate and pronounced changes as a response to water transfer while those further away respond more slowly, although the observed change appears to be longer in duration. With a rise in the groundwater level, natural vegetation responded with higher growth rates, biomass and biodiversity. These favorable changes show that it is feasible to protect and restore the degraded natural vegetation by raising the groundwater depth. Plant communities are likely to reflect the hysteresis phenomenon, requiting higher water levels to initiate and stimulate desired growth than what may be needed to maintain the plant community. Because different species have different ecologies, including different root depths and densities and water needs, their response to increasing water availability will be spatially and temporally heterogenous. The response of vegetation is also influenced by microtopography and watering style. This paper discusses strategies for the protection and restoration of the degraded vegetation in the lower reaches of the Tarim River and provides information to complement ongoing theoretical research into ecological restoration in add or semi-arid ecosystems.

The relationship between groundwater and natural vegetation in Qaidam Basin

To accurately evaluate ecological risks trigged by groundwater exploitation,it must be clarified the relationship between vegetation and groundwater.Based on remote sensing data sets MOD13Q1,groundwater table depth(WTD)and total dissolved solids(TDS),the relationship between groundwater and natural vegetation was analyzed statistically in the main plain areas of Qaidam Basin.The results indicate that natural vegetation is groundwater-dependent in areas where WTD is less than 5.5 m and TDS is less than 7.5 g/L.Aquatic vegetation,hygrophytic vegetation and hygrophytic saline-alkali tolerant vegetation are mainly distributed in areas with WTD<1.1 m.Salt-tolerant and mesophytic vegetation mainly occur in areas with WTD of 1.4-3.5 m,while the xerophytic vegetation isprimarily present in areas where WTD ranges from 1.4 m to 5.5 m.Natural vegetation does not necessarily depend on groundwater in areas with WTD>5.5 m.For natural vegetation,the most suitable water TDS is less than 1.5 g/L,the moderately suitable TDS is 1.5-5.0 g/L,the basically suitable TDS is 5.0-7.5 g/L,and the unsuitable TDS is more than 7.5 g/L.

The Linkage between Natural Vegetation, Water Dynamics and Pyrite （FeS2） Oxidation in Tidal Lowlands

The research aimed to analyze the linkage between natural vegetation, water dynamics and pyrite （FeS2） oxidation in tidal lowlands. The research was carried out in tidal lowland Pulau Rimau, South Sumatra from February to December 2010. The field observations are done by exploring several transect on land units. The field description refers to Soil Survey Staff. Water and soil samples were taken from selected key areas for laboratory analyses. The vegetation data were collected by making sample plots placed on each vegetation type with plot sizes 10 m × 10 m for secondary forests and 5 m × 5 m for shrubs and grass. The observations of surface water level were done during the river receding with units of meter above sea level （m.asl）. The results shows that pyrite formation is largely determined by the availability of natural vegetation as S （sulfur） donors, climate and uncontrolled water balance and supporting faunas such as crabs and mud shrimp. Climate and water balance as well as supporting faunas is the main supporting factors to accelerate the process of formation pyrite. Oxidized pyrite increases soil pH thus toxic to fish, arable soils, plant growth, disturbing the water quality and soil nutrient availability. Oxidized pyrite is predominantly accelerated by the dynamics of river water and disturbed natural vegetation by human activities, and the pyrite oxidation management approach is divided into three main components of technologies, namely water management, land management and commodity management.

Impacts of Mau Forest Catchment on the Great Rift Valley Lakes in Kenya

Remote sensing and GIS applications are being widely used for various projects relating to natural resource management. Forests are very important national assets for economic, environmental protection, social and cultural values and should be conserved in order to realize all these benefits. Kenya’s forests are rapidly declining due to pressure from increased population, technological innovation, urbanization human development and other land uses. Mau forest is one of the major forests in Kenya that is a catchment area for many Great Rift Valley lakes within the country and faces a lot of destruction. Continued destruction of the Mau forest will cause catastrophic environmental damage, resulting in massive food crises and compromising the livelihoods of millions of Kenyans, and the possible collapse of the tourism industry. The purpose of this research was to investigate the relationship between the increasing rate of deforestation and the reduction of the volumes of water in the neighboring lakes between the years 1989 to 2010. Satellite images from Landsat-5 Thematic Mapper (TM) and Landsat-7 Enhanced Thematic Mapper (ETM+) were used for the detection of changes in the Mau forest and the dynamics of the neighboring water bodies that included lakes: Naivasha, Baringo, Nakuru, Elementaita and Bogoria. The research showed that from a period of 1989 to 2010 Mau forest has been decreasing due to deforestation and the water bodies have irregular dynamics in that, from 1989 to 2000, there was rise in the volume of water, this is attributed to the El Nino rains experienced in the country during the year 1997 and 1998. But between 2000 and 2010 the volume decreased as the forest is also decreasing. It is recommended that the government creates awareness to sensitize the public on the importance of such forests as catchment areas in Kenya.

Response of the water use efficiency of natural vegetation to drought in Northeast China

Drought has become a problem that is universally faced by global terrestrial ecosystems. Northeast China is located in a region sensitive to global climate changes, and one of the main impacts of climate changes in Northeast China is manifested as drought in growing seasons. This study analyzes the spatio-temporal evolution law of the water use efficiency(WUE) of the main natural vegetation(i.e., cold-temperate coniferous forests, temperate pine-broad-leaved mixed forests, warm-temperate deciduous broad-leaved forests, and grasslands) in Northeast China based on public MODIS data products, including MCD12 Q1, MOD15 A2 H, MOD16 A2, and MOD17 A3 H, and meteorological data from 2002 to 2013. The influence of drought events on the WUE of different vegetation types and their response to drought events are also investigated. The study findings are as follows:(1) drought in Northeast China frequently occurs in the regions stretching from 114.55°E to 120.90°E, and the percentage of drought area among the forests is lower than that among the grasslands during these years;(2) the annual average WUE of the natural vegetation ranges from 0.82 to 1.08 C/kg^(-1) H_2O, and the WUE of forests(0.82 to 1.08 C/kg^(-1) H_2O) is universally higher than that of grasslands(0.84 to 0.99 C/kg^(-1) H_2O);(3) in 2008, the regions where the WUE in drought conditions is higher than that in normal water conditions account for 86.11% of the study area, and a significant linear positive correlation is found between the WUE in drought conditions and the WUE in normal water conditions, whereas the degree of drought does not influence the WUE of the natural vegetation in an obviously linear manner; and(4) the WUE for the cold-temperate coniferous forests and temperate pine-broad-leaved mixed forests with a high ET or low NPP is more likely to rise in drought conditions; the WUE for the grasslands with a low Evapotranspiration(ET), Net Primary Production(NPP), and Leaf Area Index(LAI) is more likely to rise in drought conditions; and the ET, NPP, and LAI have no significant influence on the WUE for the warm-temperate deciduous broad-leaved forests in drought conditions. This study contributes to improving the evaluation of the influence of drought on natural ecosystems.

兰州市南北两山土壤水分遥感反演及植被需水量估算

探究西北干旱区土壤水分和植被需水量动态变化特征,可为生态恢复不同阶段所需水资源量及水资源优化配置提供科学依据。以兰州市南北两山为研究区,基于Sentinel-2 L2A和Landsat 8 OLI遥感影像,结合实测土壤0~10 cm的111个数据,分别构建垂直干旱指数(Perpendicular Drought Index,PDI)、改进型垂直干旱指数(Modified Perpendicular Drought Index,MPDI)和植被调整垂直干旱指数(Vegetation-adjusted Perpendicular Drought Index,VAPDI)土壤水分反演模型,并采用4种模型指标定量决定系数(R^(2))、平均绝对误差(MAE)、平均相对误差(MRE)、均方根误差(RMSE)对模型反演的效果进行精度评价,选出最优的土壤水分反演模型并结合土壤水分限制系数,与研究区2019年林地、草地和耕地植被面积的空间数据、各站点生长季内的参考作物蒸散量,构建植被生态需水量模型,厘清研究区内土壤水分、植被需水量时空变化特征。结果表明:(1)2种数据源下的PDI、MPDI、VAPDI和实测数据之间均有着不同程度的线性负相关性,其中R^(2)分别为0.37、0.64和0.59,从评价指标的结果来看,MPDI的土壤水分回归模型的拟合决定系数最高,2种遥感数据反演的土壤水分空间分布格局具有一致性。(2)分辨率高的Sentinel-2L2A土壤水分反演更加精细,土壤水分整体呈波动增长趋势,多时段土壤水分的平均值为23.27%,呈现出降低再增加然后下降,总体增幅为74.07%。(3)兰州市南北两山4—10月植被需水量月均值也呈现先增加后下降的趋势,与土壤水分含量变化具有一致性,4—10月中7月植被需水量最大,为3.98×10^(7)m^(3),10月植被生态需水量最小,为0.97×10^(7)m^(3)。随着环境绿化工程的实施,兰州市南北两山从只能生长耐旱草本和低矮灌木的植物,逐步形成以多种类结合的群落结构。本研究可为兰州市南北两山土壤水资源合理利用及植被恢复提供参考。

Analysis on the ecological benefits of the stream water conveyance to the dried-up river of the lower reaches of Tarim River,China

This paper analyzes the monitored data of the 4 times of stream water conveyances to the river section where the stream flow was cut-off, of 9 groundwater-monitoring sections and 18 vegetation plots in the lower reaches of Tarim River. The results show that the groundwater depth in the lower reaches of Tarim River rose from 9.87 m before the conveyances to 7.74 m and 3.79 m after the first and second conveyances, 3.61 and 3.16 m after the 2 phases of the third conveyance, and 2.66 m after the fourth conveyance. The transverse response scope of groundwater level was gradually enlarged along both sides of the channel of conveyances, i.e., from 450 m in width after the first conveyance to 1050 m after the fourth conveyance, but the response degree of groundwater level was reduced with the increase of the distance away from the channel of conveyances. The composition, distribution and growth status of the natural vegetation are directly related to the groundwater depth. The indexes of Simpson’s biodiversity, McIntosh’s evenness and Margalef’s richness, which reflect the change of the quantity of species and the degree of biodiversity, are reduced from 0.70, 0.48 and 0.90 to 0.26, 0.17 and 0.37 re- spectively along with the drawdown of groundwater level from the upper reaches to the lower reaches. After the stream water conveyances, the natural vegetation in the lower reaches is saved and restored along with the rise of groundwater level, the response scope of vegetation is gradually enlarged, i.e., from 200— 250 m in width after the first conveyance to 800 m after the fourth conveyance. However, there is still a great disparity to the objective of protecting the “Green Corridor”in the lower reaches of Tarim River. Thus, it is suggested to convey the stream water in double-channel way, combine the conveyance with water supply in surface scope, or construct the modern pipe-conveyance network systems so as to save the natural vegetation in an intensive way, achieve the efficient water consumption and speed up the restoration and re- generation of the damaged ecosystems in the lower reaches of Tarim River.

近30年吐鲁番哈密地区植被生态需水估算

新疆吐鲁番哈密地区(简称“吐哈地区”)属极端干旱区,光照时间长、昼夜温差大,生态环境脆弱,生态环境问题尤为突出,水资源有效利用对生态环境保护具有重要作用。吐哈地区植被生态需水在总需水量中占据显著比重,对于维护区域生态平衡和可持续发展具有重要意义。基于生态保护重要性分级,统计研究区总植被面积与各生态保护等级区植被面积,分别采用改进的彭曼公式法、潜水蒸散发法与生态分区综合计算法估算1990—2020年吐哈地区不同生态保护等级的植被生态需水量。结果表明:(1)三种方法估算的吐哈地区总植被生态需水量在1990—2020年期间呈现波动变化,改进的彭曼法估算结果由50.18亿m^(3)变化到57.8亿m^(3),潜水蒸散法估算结果由54.42亿m^(3)变化到51.85亿m^(3),生态分区估算结果由45.58亿m^(3)变化到52.03亿m^(3)。(2)极重要生态保护等级区的近30年植被需水量在三种估算方法下均增长,其中改进的彭曼公式法估算结果增长最大,由12.12亿m^(3)增长到18.54亿m^(3)。(3)对比三种植被生态需水估算方法,1990—2020年每5年期间估算的植被生态需水总量变化趋势基本一致,每种方法估算的相应生态保护等级区内植被生态需水量变化趋势一致,说明生态分区估算植被生态需水量的方法是合理的,可为植被生态需水的估算提供参考。

The impact of vegetation restoration on erosion-induced sediment yield in the middle Yellow River and management prospect

According to the characteristics of water and erosion environments of different natural zones on the Loess Plateau, this paper studies changes of vegetation types, distribution boundaries of forest and grass as well as restoration capacity of vegetation in different natural zones in the middle Yellow River. The annual precipitation of 530 mm is the critical annual pre-cipitation for forest and grass distribution in the middle Yellow River. Among the zonal and azonal environmental factors affecting watershed sediment yield, the intermediate diameter D50 (mm) of suspended load and forest coverage (V, %) play the leading role. Of them the effect weight of forest coverage (V, %) on catchments sediment yield is only 3.4% less than the role of the intermediate diameter (D50, mm), they are almost the same. To effectively control soil erosion in semiarid, especially in hilly-gullied areas and make sediment transport modulus reduce to less than 6000 t/km2, it is rather difficult by merely relying on natural restoration of forest. In the process of cultivated land conversion into forest land and grassland, measures suiting local conditions should be adopted in tree species selection and artificial afforestation (grass planting) based on management with biological measures for slopeland and engineering measures for hilly-gullied areas, so that watershed forest coverage in key counties can reach at least over 30%.Compared with the standard period of precipitation prior to the 1960s, with the decrease of an-nual precipitation at various periods, plant productivities decline to different degrees under natural conditions. The main reason accountable for the low survival rate of new seedlings and grass over years is due to precipitation decrease. In light with regression models of annual pre-cipitation and natural vegetation productivities, it is possible to obtain estimated values of wa-tershed natural vegetation productivity and eco-water consumption needed for the restoration to the standard period respectively for the present time or arbitrary period since the 1970s, thus providing a scientific basis for forest and grassland restoration in the middle Yellow River and the management prospect.

塔里木河下游地下水位对植被的影响

对塔里木河下游断流河道2000～2002年9个地下水监测断面和18个植被样地的实地监测资料分析表明,地下水埋深对天然植被的组成、分布及长势有直接关系.地下水位的不断下降和土壤含水率大大丧失是引起塔里木河下游植被退化的主导因子.塔里木河下游的四次输水对其下游地下水位抬升起到了积极作用,河道附近地下水位呈逐级抬升过程,横向影响范围达1000 m左右,纵向上,表现为上段地下水抬升幅度较大(达84%),下段抬升幅度较小(6%).随着地下水位的抬升,天然植被的响应范围由第一次输水后的200～250 m,扩展到第四次输水的800 m.

植被生态需水研究进展及展望

生态需水研究是目前生态学和水文学、水资源学研究的热点领域。植被生态需水研究不仅是其中的重要研究内容,而且对于指导区域植被生态恢复与生态建设也具有重要意义。本文在调研有关研究文献的基础上,对植被生态需水的概念与内涵、计算方法进行了分析。认为植被生态需水是指为了保证植被生态系统能够健康维持,并确保其生态服务功能得到正常发挥而必须消耗的一部分水量。在区域植被生态需水量的计算中,最关键的是对单位面积、单位时间内某一植被类型生态需水定额的确定,目前常用的计算方法多是基于农业气象学原理的直接计算法。

干旱区天然植被生态需水量计算方法

依据生态适宜性理论,建立了植物生长与地下水位关系的对数正态分布模型;基于此模型,结合遥感技术进行的生态分区和植物生理需水的现场实验数据,提出了干旱区天然植被生态需水量计算方法;应用此方法计算了黑河流域额济纳旗天然植被生态需水量,计算成果与其他成果比较相差较小。结果表明,该计算方法是合理的,可以推广应用于干旱区其他地区。

中国西北地区生态需水研究(1)——干旱半干旱地区生态需水理论分析

水是西北地区生态的关键生境要素,西北地区严重的生态环境问题使得生态需水随着西部开发受到广泛的关注。论文指出生态需水所涉及的理论问题,从生态系统稳定性探讨原始天然生态系统的适宜开发强度,在此基础上,遵循可持续发展的生态观探讨西北地区生态保护与生态建设的模式;从地带性理论和径流形成原理分析西北地区各类自然地理单元上的植被需水规律,从而明确了自然界哪些生态完全靠降水支撑、哪些生态除降水之外还需径流支撑,用生态的排序方法进一步分析干旱地区地下水埋深与植被类型的关系。同时,通过分析土地利用变化与径流形成的关系,以及生物与环境的不可分割性与物竞天择的自然选择原理给出生态需水的概念,从而为量化生态需水提供了理论依据。

疏勒河中游绿洲天然植被生态需水量估算与预测研究

以疏勒河流域中游绿洲为研究区,借助统计分析法、遥感和GIS技术方法对2013年疏勒河中游绿洲遥感影像土地利用覆盖变化进行解译与分析,得出各种天然植被覆盖状况数据,利用典型的潜水蒸发模型—阿维里扬诺夫公式对研究区内各县区的天然植被生态需水量进行了估算,并对未来天然植被面积和生态需水量进行了预测,为区域生态环境保护与水资源合理分配提供参考。结果表明：疏勒河中游绿洲现状天然植被最小生态需水量为18 768.97×104m3,最大生态需水量为46643.04×10^4m^3,其中,天然林地生态需水量为1 187.71×10^4-2 898.72×10^4m^3,天然草地生态需水量为17 581.27×10^4-43 744.32×10^4m^3,瓜州天然植被生态需水量为9 685.06×10^4-23 392.09×10^4m^3,玉门天然植被生态需水量6 552.11×10^4-17 133.45×10^4m^3,敦煌天然植被生态需水量为2 531.80×10^4-6 117.50×10^4m^3。2020年疏勒河中游绿洲天然植被生态需水量预测为20 655.96×10^4-66 614.75×10^4m^3,其中,天然林地生态需水量为1 316.57×10^4-3 855.91×10^4m^3,天然草地生态需水量为19 339.39×10^4-62 758.84×10^4m^3;2030年疏勒河中游绿洲天然植被生态需水量预测为22 721.55×10^4-85 584.09×10^4m^3,其中,天然林地生态需水量为1 448.22×10^4-4970.08×10^4m^3,天然草地生态需水量为21 273.33×10^4-80 614.01×10^4m^3。研究结果对促进疏勒河流域生态水权研究、水量分配以及区域生态保护、水资源合理配置与经济社会协调可持续发展具有重要参考意义。指出未来应进一步加强人类活动影响下区域天然植被需水规律研究、不同生态功能区植被生态需水规律以及基于生态保护目标的区域生态需水量及阈值研究。

黄土高原地区森林植被生态需水研究

水土流失是黄土高原面临的主要生态问题 ,而退耕还林还草、恢复植被是治理水土流失、改善生态环境的必然选择 .但黄土高原位于干旱半干旱地区 ,水资源匮乏是影响该地区植被生态建设的根本因子 .因此 ,植被生态需水研究对于该地区的生态环境建设具有极其重要的意义 .本文根据最新遥感图像资料 ,在GIS支持下 ,计算了黄土高原地区现有林地生长季的最小生态需水量和适宜生态需水量 ,其结果分别为 2 6 2 4 9× 10 8m3 和 4 2 1 34× 10 8m3 .除去降雨对林地耗水的补给外 ,以最小生态需水量为标准 ,则黄土高原地区在生长季发生水分亏缺的林地面积为 76 39 0 9km2 ,占现有林地总面积的 9 1% ,亏缺水量为 4 77× 10 8m3 ;以适宜生态需水量为标准 ,则有 5 7 7%的现有林地在生长季中发生水分亏缺 ,亏缺水量为 5 8 5 5× 10 8m3 .

基于地下水恢复的塔里木河下游生态需水量估算

为探明生态输水后地下水响应带范围及地下水恢复下生态需水量,以塔里木河下游大西海子水库至台特玛湖段为研究区,基于2000—2010年生态输水和地下水埋深分布特征,分析了塔里木河下游生态输水后两岸地下水位恢复状况,并借助遥感和地理信息系统技术对研究区生态需水量进行了研究。结果表明:塔河下游地下水位的抬升幅度与输水量的大小呈一定的正相关关系,并存在一定的时效性。2004—2010年地下水处于长期的负均衡状态,多年下降幅度明显。塔河下游英苏、喀尔达依、阿拉干和依干不及麻断面地下水响应幅度分别为1195、1050、2281 m和1000 m。历经11a输水后,塔里木河下游地下水总恢复需水量为7.06×108m3,其中,齐文阔尔河段为4.98×108m3,老塔里木河段为2.09×108m3,地下水恢复至生态水位4.5m需要5—8a的时间。保护塔里木河下游大西海子以下所有天然植被面积(96114.09 hm2)的生态需水量为0.587×108m3,保护下游地下水响应带天然植被面积(41439.85 hm2)的生态需水量为0.21×108m3。

基于农业气象学原理的林地生态需水量估算——以泾河流域为例

从农业气象学原理出发 ,森林植被的生态需水可以理解为林地的蒸散耗水量。根据土壤水分有效性的划分 ,林木暂时凋萎含水量和生长阻滞含水量分别是能保证林木基本生存和正常生长时土壤含水量的下限 ,据此可以作为林地最小生态需水定额和适宜生态需水定额计算的依据 ,其数值通过计算林地的潜在蒸散并利用土壤水分修正系数和林木系数进行订正获得。根据遥感图像资料 ,在 GIS支持下 ,计算了泾河流域现有林地生长季的最小生态需水量和适宜生态需水量 ,分别为 2 0 396 0× 10 4 m3和340 330× 10 4 m3。

黑河下游分水后的植被变化初步研究

黑河下游地区近年来由于河水注入量的持续减少,使得依赖河水补给的地下水相应减少,造成区域性地下水位下降,从而出现了一系列的生态环境问题.大面积湿地消失,天然植被全面衰败,土地盐化加剧,胡杨和沙枣林面积减少,并以老林为主.红柳灌丛也减少,并且多已成为稀疏矮化的群落.各种禾草草甸严重退化,多以演替成苦豆子群落.为了恢复和重建受损的下游生态系统,2 0 0 0年7月开始,实施了黑河下游应急生态输水工程,水流于2 0 0 2年7月17日流进黑河尾闾端的东、西居延海,使干涸10年的居延海重新受到水的滋润.作者根据近三年黑河下游分水前后地下水位和植被等项内容的监测资料,探讨了地下水位与天然植被生长的相互关系.研究结果表明:分水使得该地区生态环境有了较大的改善,地下水位普遍抬升;胡杨林得到恢复;灌木荒漠植被得到部分恢复;

吉林西部植被生态环境需水量供需平衡研究

吉林西部地处半湿润、半干旱气候区,水资源的紧缺已成为制约生态环境修复和地区经济发展的重要因素。在对已往生态环境需水量研究成果进行总结,分析该区自然环境的基础上,提出了植被生态环境需水量的概念,即保证植物正常、健康生长,同时能够抑制土地沙化、碱化,乃至荒漠化发展所需的最小水资源量。采用统计年鉴资料,并利用TM卫星影像解译数据进行修正,计算出了农田、草地和林地面积。分别采用面积定额法、水量平衡法、潜在蒸散量法求得农田、草地和林地的生态环境需水量,分别为60 698亿,42 942亿和32 852亿m3。通过供需水平衡分析,得出该区植被生态环境需水量为136 492亿m3,尚缺水19 25亿m3。