Relating Trends in Streamflow to Anthropogenic Influences: A Case Study of Himayat Sagar Catchment,India

Catchment development has been identified as a potentially major cause of streamflow change in many river basins in India. This research aims to understand changes in the Himayat Sagar catchment (HSC), India, where significant reductions in streamflow have been observed. Rainfall and streamflow trend analysis for 1980–2004 shows a decline in streamflow without significant changes in rainfall. A regression model was used to quantify changes in the rainfall-runoff relationship over the study period. We relate these streamflow trends to anthropogenic changes in land use, groundwater abstraction and watershed development that lead to increased ET (Evapotranspiration) in the catchment. Streamflow has declined at a rate of 3.6 mm/y. Various estimates of changes in evapotranspiration/irrigation water use were made. Well inventories suggested an increase of 7.2 mm/y in groundwater extractions whereas typical irrigation practices suggests applied water increased by 9.0 mm/y, while estimates of evapotranspiration using remote sensing data showed an increasing rate of 4.1 mm/y. Surface water storage capacity of various small watershed development structures increased by 2 mm over 7 years. It is concluded that the dominant hydrological process responsible for streamflow reduction is the increase in evapotranspiration associated with irrigation development, however, most of the anthropogenic changes examined are interrelated and occurred simultaneously, making separating out individual impacts very difficult.     

Quantifying the Poorly Known Role of Groundwater in Agriculture: the Case of Cyprus

Agriculture in the Mediterranean region is constrained by limited water resources and in many countries irrigation demand exceeds the renewable water supply. This paper presents a comprehensive approach to (a) quantify the consumptive green (soil moisture provided by precipitation) and blue (irrigation) water use for crop production, (b) distinguish the contribution of groundwater to irrigation supply and (c) estimate groundwater over-abstraction. A spatiotemporally explicit soil water balance model, based on the FAO-56 dual crop coefficient approach, which includes the computation of evaporation losses of the different irrigation systems, was applied to the 5,760-km² area of the Republic of Cyprus for the agro-meteorological years 1995–2009. The model uses national agricultural statistics, community-level data from the agricultural census and daily data from 34 meteorological stations and 70 precipitation gauges. Groundwater over-abstraction is quantified per groundwater body, based on the sustainable abstraction rates specified in the Cyprus River Basin Management Plan, as prepared for the EU Water Framework Directive. It was found that, on average, total agricultural water use was 506 Mm³/year, of which 62 % is attributed to green water use and 38 % to blue water use. Groundwater contributed, on average, 81 % (151 Mm³/year) to blue water use and exceeded the recommended abstraction rates by 45 % (47 Mm³/year). Even though the irrigated area decreased by 18 % during the 2008 drought year, relative to the wettest year (2003), total blue water use decreased by only 1 %. The limited surface water supply during the driest year resulted in a 37 % increase in groundwater use, relative to the wettest year, and exceeded the sustainable abstraction rate by 53 % (55 Mm³/year). Overall, the model provides objective and quantitative outcomes that can potentially contribute to the improvement of water resource management in Mediterranean environments, in the light of climate change and expected policy reforms.     

黄土高塬沟壑区绿水对土地利用和气候变化的响应研究——以南小河沟流域为例

黄土高原地区生态环境脆弱,水资源十分匮乏,生产、生活和生态用水受到严重威胁。本文选择黄土高塬沟壑区典型小流域——南小河沟流域为研究对象,分别采用水量平衡法和Zhang模型法评价了该流域1954—2012年的绿水资源量,利用Mann-Kendall统计检验法对年绿水量进行了趋势分析和突变点检验,并探讨了绿水对土地利用和气候变化的响应规律,定量评价了两者变化对绿水的影响。结果表明:与水量平衡法相比,Zhang模型法的拟合结果较好,流域多年绿水资源量为443.2 mm,年绿水量呈不显著的下降趋势,突变时间发生在1978年;各土地利用类型绿水的年际变化不均,其中林地绿水量最大,草地次之,建筑用地最小;气候变化对绿水的影响中,降水是影响绿水的主要限制因素;根据情景分析法的计算结果,1954—2012年期间气候因素和土地利用因素对绿水变化的贡献率分别为123.6%和-23.6%,分离评判法的计算结果为137.7%和-37.7%,因此气候变化对绿水的影响要远大于土地利用变化,而林地面积增加是土地利用变化使绿水量增加的原因。该研究可为黄土高原区域生态环境恢复、区域水资源规划管理提供合理有效的理论依据。     

Simulation-Optimization Modeling for Conjunctive Use Management under Hydrological Uncertainty

The canal water supply, which is the only source of irrigation, in the rice-dominated cropping system of the Hirakud canal command (eastern India) is able to meet only 54 % of the irrigation demand at 90 % probability of exceedance. Hence, considering groundwater as the supplemental source of irrigation, conjunctive use management study by combined simulation-optimization modelling was undertaken in order to predict the maximum permissible groundwater pumpage from the command area. Further, optimal land and water resources allocation model was developed to determine the optimal cropping pattern for maximizing net annual return. The modelling results suggested that 2.0 and 2.3 million m³ of groundwater can be pumped from the bottom aquifer during monsoon and non-monsoon seasons, respectively, at 90 % probability of exceedance of rainfall and canal water availability (PERC). Optimal cropping patterns and pumping strategies can lead to about 51.3–12.5 % increase in net annual return from the area at 10–90 % PERC. The sensitivity analysis of the model indicates that the variation in the market price of crops has very high influence on the optimal solution followed by the cost of cultivation and cultivable area. Finally, different future scenarios of land and water use were formulated for the command area. The adoption of optimal cropping patterns and optimal pumping strategies is strongly recommended for sustainable management of available land and water resources of the canal command under hydrological uncertainties.     

Evapotranspiration from a Mixed Deciduous Forest Ecosystem

The objectives of this paper were to determine evapotranspiration (ET) from an oak-beech dominated forest ecosystem in Belgrad Forest near Istanbul, Turkey by using catchment water balance method and compare it with potential evapotranspiration (PET) computed by using Thornthwaite method. Data, in this study, were derived from a long-term hydrological research conducted in Belgrad Forest. Long-term stream flow measurements (1979–1995) were conducted with concrete sharp-crested V-notch weirs instrumented with automatic water level recorders in two close experimental watersheds. ET values of the watersheds were determined by using water balance equation. Average annual ET values from the old growth oak-beech forest ecosystem during the monitoring period of 17 years were around 833.20 mm for W-I and 752.07 mm for W-IV whereas PET estimated according to Thornthwaite method was found to be 726.14 mm. In other words, 79.68%, and 71.93% of mean annual precipitation evaporated from W-I and W-IV, respectively while 69.45% of precipitation evaporated according to Thornthwaite method. PET estimated with Thornthwaite method differed significantly only from W-I whereas W-I and W-IV had similar ET values.     

Effects of Land-Use and Climate Change on Hydrological Processes in the Upstream of Huai River, China

Land use/land cover and climate change can significantly alter water cycle at local and regional scales. Xixian Watershed, an important agricultural area in the upper reach of the Huaihe River, has undergone a dramatic change of cultivation style, and consequently substantial land use change, during the past three decades. A marked increase in temperature was also observed. A significant monotonic increasing trend of annual temperature was observed, while annual rainfall did not change significantly. To better support decision making and policy analysis relevant to land management under climate change, it is important to separate and quantify the effect of each factor on water availability. We used the Soil and Water Assessment Tool (SWAT), a physically based distributed hydrologic model, to assess the impact of Land use and climate changes separately. The SWAT model was calibrated and validated for monthly streamflow. Nash-Sutcliff efficiency (NSE), percentage bias (PBIAS), and coefficient of determination (R ²) were 0.90, 6.3 %, and 0.91 for calibration period and 0.91, 6.9 %, and 0.911 for validation period, respectively. To assess the separate effect of land use and climate change, we simulated streamflow under four scenarios with different combinations of two-period climate data and land use maps. The joint effect of land use and climate change increased surface flow, evapotranspiration, and streamflow. Climate variability increased the surface water and stream-flow and decreased actual evapotranspiration; and land use change played a counteractive role. Climate variability played a dominant role in this watershed. The differentiated impacts of land-use/climate variabilities on hydrological processes revealed that the unapparent change in stream-flow is implicitly because the effects of climate variability on hydrological processes were offset by the effects of land use change.     

Deep soil water recharge response to precipitation in Mu Us Sandy Land of China

Soil water is the main form of water in desert areas, and its primary source is precipitation, which has a vital impact on the changes in soil moisture and plays an important role in deep soil water recharge (DSWR) in sandy areas. This study investigated the soil water response of mobile sand dunes to precipitation in a semi-arid sandy area of China. Precipitation and soil moisture sensors were used to simultaneously monitor the precipitation and the soil water content (SWC) dynamics of the upper 200-cm soil layer of mobile sand dunes located at the northeastern edge of the Mu Us Sandy Land of China in 2013. The data were used to analyze the characteristics of SWC, infiltration, and eventually DSWR. The results show that the accumulated precipitation (494 mm) from April 1 to November 1 of 2013 significantly influenced SWC at soil depths of 0–200 cm. When SWC in the upper 200-cm soil layer was relatively low (6.49%), the wetting front associated with 53.8 mm of accumulated precipitation could reach the 200-cm deep soil layer. When the SWC of the upper 200-cm soil layer was relatively high (10.22%), the wetting front associated with the 24.2 mm of accumulated precipitation could reach the upper 200-cm deep soil layer. Of the accumulated 494-mm precipitation in 2013, 103.2 mm of precipitation eventually became DSWR, accounting for 20.9% of the precipitation of that year. The annual soil moisture increase was 54.26 mm in 2013. Accurate calculation of DSWR will have important theoretical and practical significance for desert water resources assessment and ecological construction.     

Variable Streamflow Contributions in Nested Subwatersheds of a US Midwestern Urban Watershed

Quantification of runoff is critical to estimate and control water pollution in urban regions, but variation in impervious area and land-use type can complicate the quantification of runoff. We quantified the streamflow contributions of subwatersheds and the historical changes in streamflow in a flood prone urbanizing watershed in US Midwest to guide the establishment of a future pollution-control plan. Streamflow data from five nested hydrological stations enabled accurate estimations of streamflow contribution from five subwatersheds with variable impervious areas (from 0.5% to 26.6%). We corrected the impact of Missouri river backwatering at the most downstream station by comparing its streamflow with an upstream station using double-mass analysis combined with Bernaola-Galvan Heuristic Segmentation approach. We also compared the streamflow of the urbanizing watershed with seven surrounding rural watersheds to estimate the cumulative impact of urbanization on the streamflow regime. The two most urbanized subwatersheds contributed >365 mm streamflow in 2012 with 657 mm precipitation, which was more than fourfold greater than the two least urbanized subwatersheds. Runoff occurred almost exclusively over the most urbanized subwatersheds during the dry period. The frequent floods occurred and the same amount of precipitation produced ~100 mm more streamflow in 2008–2014 than 1967–1980 in the urbanizing watershed; such phenomena did not occur in surrounding rural watersheds. Our approaches provide comprehensive information for planning on runoff control and pollutant reduction in urban watersheds.     

Assessment of Water Resources Availability and Groundwater Salinization in Future Climate and Land use Change Scenarios: A Case Study from a Coastal Drainage Basin in Italy

The joint effect of changes in climate and land use on the future availability of water resources was assessed under the SRES A1B and A2 climate scenarios as well as five land use scenarios for the 2080–2100 time-frame in an Italian coastal watershed. The study area is a small coastal polder (100 km²) characterized by irrigated agriculture, urban expansion, drainage, quarrying and sensitivity to salt-water intrusion. The hydroclimatic budget and the GALDIT index have been computed for assessing water resources availability and groundwater vulnerability to salinization, respectively. The methodology developed is integrated into a tool based on Excel?, which supported the development of scenarios in participatory processes. The conclusions emerged from the analysis are the following: (1) climate change is more effective than land use change in controlling future freshwater availability and amplifies the imbalance between winter surplus and summer deficits, (2) freshwater availability in the summer will likely be affected by an increase in evaporation from open water surfaces due to increased temperature, whereas winter surplus would increase, (3) the vulnerability of the coastal aquifer to salinization will probably moderately increase but an inherent limitation of the GALDIT index to land use change parameters prevents a sound assessment. Strategies that may be proposed to administrators and stakeholders are based on increasing storage of seasonal water surplus.     

降水和下垫面对流域径流量影响的定量研究

定量分析降水和下垫面变化对径流的影响,对流域水资源规划管理具有重要的意义。以北京市漫水河流域为研究对象,对漫水河1956-2016年年降水量、天然径流量的变化趋势及突变性进行了分析,以径流变异前1956-1979时间段为基准期,建立降水径流双累积曲线关系,识别与基准期相比不同时期降水和下垫面条件变化对天然径流的贡献率。结果表明:2000年以后流域内耗水、水利工程调蓄水等人类活动的直接影响有所减少,与1956-1979年基准期相比,1990-1999年降水量的影响程度大于下垫面,为63. 9%; 1980-1989、2000-2009、2010-2016年3个时期下垫面对径流量减少的影响程度均大于降水,降水量和下垫面对径流量减少的贡献率分别为44. 9%和55. 1%、47. 9%和52. 1%、44. 5%和55. 5%。     

Effect of Substitute Water Projects on Tempo-Spatial Distribution of Groundwater Withdrawals in Chikugo-Saga Plain,Japan

Due to large-scale agricultural irrigation and industrial production, groundwater had been excessively employed to benefit the economy development and life improvement in Chikugo-Saga plain since the middle of last century, which led to many environmental problems such as land subsidence, flooding inundation and water shortage. In order to mitigate the impact of environmental hazards, some water supply projects have been performed to substitute surface water for groundwater since 1970s. For the purpose of comprehending the influence of substitute water projects on groundwater withdrawals, a tempo-spatial groundwater withdrawals assessment model with the resolution of one month in time and one kilometer in space was initially established based on various data concerning meteorology, agriculture, land use, soils, surface water consumption and groundwater utilization by using GIS. According to the development of the substitute water projects, a 28-year study period 1979–2006 was then divided into four stages (i.e. 1979–1984, 1985–1995, 1996–2000 and 2001–2006) and the tempo-spatial distribution of groundwater withdrawals for each stage was represented by means of the proposed model. The tempo-spatial variation of groundwater withdrawals for various water use categories under the effect of substitute water projects was finally analyzed by comparing the distributions of groundwater withdrawals at different stages. The results show that with the advance of the substitute water projects studied, the groundwater pumpage for irrigation, industry or waterworks varies geographically and phasically in the plain. From the first stage to the last stage, there is a significant decrease by approximately 23 % in mean annual total groundwater withdrawals. During the study period, dramatic declines are found in agriculture-use groundwater pumpage in the downstream land of Chikugo river at the third stage, in industry-use pumpage in eastern Saga area at the second stage and found in waterworks-use pumpage in western Saga area at the last stage, while little change in agriculture-use pumpage in western Saga area and in industry-use pumpage in Chikugo area without the corresponding substitution projects. Moreover, it is indicated that the proposed assessment model of groundwater withdrawals is helpful to figure out the regional groundwater exploitation and its impact on the environment, particularly when there is the lack of groundwater pumpage data recorded. It is necessary to develop new substitute water supply plans to reduce the agriculture-use groundwater withdrawals in western Saga area and the industry-use withdrawals in Chikugo area, for more effective management of regional water resources in future.     

Numerical Analysis of Surface Runoff for the Liudaogou Drainage Basin in the North Loess Plateau,China

The aim of this study is to realize a distribution hydrological model to calculate the rainfall-runoff process precisely for the development of the ravine in the north Loess Plateau. On the basis of the real investigation result to the vertical profile of soil in the Liudaogou drainage basin, which is located in the ravine of wind-water erosion crisscross region in the northern Loess Plateau, a vertical profile model for soil in the study area was set up, and a distribution-type hydrological model was developed by combining GIS with kinematic wave theory. This model was subsequently applied in the experimental drainage basin. The numerical simulation results show that the calculation of the rainfall-runoff process has relatively high precision (error less than 3 %). The model was used to calculate the rainfall-runoff process for 5 years (2005–2009) in the experimental drainage basin to deduce the yearly surface runoff volume and the annual runoff coefficient. The calculated average runoff coefficient for 2005–2009 is 0.11, and the average 5 year precipitation (437 mm) is almost equal to the yearly average precipitation, indicating that the annual runoff coefficient of the experimental drainage basin is approximately 0.10 to 0.15. The study provides a practical numerical method for estimating surface water resources for the wind-water erosion crisscross region of the northern Loess Plateau.     

Forecasting of Multi-Step Ahead Reference Evapotranspiration Using Wavelet- Gaussian Process Regression Model

Evapotranspiration is one of the most important components in the optimization of water use in agriculture and water resources management. In recent years, artificial intelligence methods and wavelet based hybrid model have been used for forecasting of hydrological parameters. In present study the application of the Gaussian Process Regression (GPR) and Wavelet-GPR models to forecast multi step ahead daily (1–30 days ahead) reference evapotranspiration at the synoptic station of Zanjan (Iran) were investigated. For this purpose a 10-year statistical period (2000–2009) was considered, 7 years (2000–2006) for training and the final three years (2007–2009) for testing the various models. Various combinations of input data (various lag times) and different kinds of mother wavelets were evaluated. Results showed that, compared to the GPR model, the hybrid model Wavelet-GPR had greater ability and accuracy in forecasting of daily evapotranspiration. Moreover, the use of yearly lag times in the GPR and wavelet-GPR model increased its accuracy. Investigation of various kinds of mother wavelets also indicated that the Meyer wavelet was the most suitable mother wavelet for forecasting of daily reference evapotranspiration. The results showed that by increasing the forecasting time period from 1 to 30 days, the accuracy of the models is reduced (RMSE = 0.068 mm/day for one day ahead and RMSE = 0.816 mm/day for 30 days ahead). Application of the proposed model to summer season showed that the performance of the model at summer season is better than its performance throughout the year.     

Modeling Water Resources and River-Aquifer Interaction in the Júcar River Basin,Spain

The paper presents how to solve some practical problems of water planning in a medium/large river basin, such as: the water resources assessment and its spatial-temporal variability over the long-short term, the impact of human activities on the water cycle, due to groundwater pumping and water returns into aquifers, the river-aquifer interactions and the aquifer depletion. It is based on the use of a new monthly conceptual distributed water balance model -PATRICAL- that includes the surface water (SW), groundwater (GW) behavior and the river-aquifer interaction. The model is applied to the Júcar River Basin District (RBD) in Spain (43,000 km²), with more than 250 aquifers, including catchments with humid climates (Júcar RBD northern), semiarid and arid catchments (southern). The model has a small number of parameters and obtains a satisfactory performance in SW and GW behavior. It has been calibrated/validated using monthly streamflows and two additional elements not generally used in models for large river basins, GW levels and river-aquifer interactions. In the hydrological time series of the Júcar RBD headers a statistical change point in the year 1979/80 is detected. It is due to changes in precipitation patterns and represents a 40 % of reduction in streamflows in relation with the previous period. The impact of GW pumping in all aquifers is determined, the ‘Mancha Oriental’ aquifer produces a significant reduction in streamflows of the Júcar river –around 200–250 hm³/year. The GW level in the ‘Villena-Benejama’ aquifer -Vinalopo Valley- has declined more than 200 m in last 30 years.     

Sensitivity Analysis of Coupled Hydro-Economic Models: Quantifying Climate Change Uncertainty for Decision-Making

The paper assessed the sensitivity of an integrated hydro-economic model, to provide a quantitative range of uncertainty in the impacts of climate change on water balance components and water use in the agricultural sector of Apulia region located in a semi-arid Mediterranean climate area in southern Italy. Results show that the impacts of climate change are expressed in the future by an increase in the net irrigation requirements (NIRs) of all crops. Total cultivated land is reduced by 8.5 % in the future, and the percentage of irrigated land decreases from 31 to 22 % of total agricultural land. Reduction in the irrigated land, together with the variation in the cropping pattern and the adoption of the different irrigation techniques, led to a decrease in water demand for irrigation across the entire region. The sensitivity analysis shows that the groundwater recharge has the lowest correlation to climatic parameters. Results are addressed to the scientific community and decision makers to support the design of adequate adaptation policies for efficient water management under the severe drought conditions that are likely to occur in the region according to climate change projections.     

宁夏引黄灌区适宜生态需水估算

为实现黄河水资源的可持续利用,合理配置有限的水资源,在充分掌握相关资料的基础上,对宁夏引黄灌区非农地(荒地)、湖泊湿地、人工防护林、城市以及地质的适宜需水量采用相应的计算方法进行计算并汇总进行分析。结果表明：在现状条件下,平水年份(降水频率50％)灌区周边的适宜生态需水量为 11.12亿m3,枯水年份(降水频率75％)灌区周边的适宜生态需水量为12.72亿m3,该成果可为灌区基于生态的水资源合理配置提供科学依据。     

Socio-Economic Impact of Evaporation Losses from Reservoirs Under Past, Current and Future Water Availability Scenarios in the Semi-Arid Segura Basin

This study assesses evaporation losses from water reservoirs in the semi-arid Segura basin (south-east Spain), one of the most water stressed European catchments. These losses are evaluated from both the hydrologic and economic perspectives under different water availability scenarios that are based on water policy trends and climate change predictions. We take a multidisciplinary approach to the analysis, combining energy balance models to assess the effect of climate change on evaporation from water bodies, Class-A pan data and pan coefficients to determine evaporation loss on a regional scale, and non-linear mathematical programming modelling to simulate the economic impact of water use and allocation in the basin. Our results indicate that water availability could be reduced by up to 40 % in the worst-case scenario, with an economic impact in the 32–36 % range, depending on the indicator in question. The total annual evaporation loss from reservoirs ranges from 6.5 % to 11.7 % of the water resources available for irrigation in the basin, where evaporation from small reservoirs is more than twice that from large dams. The economic impact of such losses increases with water scarcity, ranging from 4.3 % to 12.3 % of the value of agricultural production, 4.0 % to 12.0 % of net margin, 5.8 % to 10.7 % of the irrigated area, and 5.4 % to 13.5 % of agricultural employment. Results illustrate the importance of evaporation losses from reservoirs in this region and the marked upward trend for future scenarios. Besides, they highlight the extent of the impact of climate change on future water resources availability and use in southern Europe.     

Estimation of Groundwater Recharge from the Rainfall and Irrigation in an Arid Environment Using Inverse Modeling Approach and RS

Quantifying recharge from agricultural areas is important to sustain long-term groundwater use, make intelligent groundwater allocation decisions, and develop on-farm water management strategies. The scarcity of data in many arid regions, especially in the Middle East, has necessitated the use of combined mathematical models and field observations to estimate groundwater recharge. This study was designed to assess the recharge contribution to groundwater from rainfall and irrigation return flow in the Mosian plain, west of Iran. The Inverse modeling approach and remote sensing technology (RS) were used to quantify the groundwater recharge. The recharge for steady–state conditions was estimated using the Recharge Package of MODFLOW. The land-use map for the research area was produced using remote sensing and satellite images technology. According to results, groundwater recharge from the rainfall and irrigation return flow was at the rate of 0.15 mm/day. The recharge to the groundwater from rainfall was about 0.08 mm/day (10.8 % of total rainfall). The average of groundwater recharge contribution in the study area was about 0.39 mm/day that include 15.2 % of the total water used in the irrigated fields. We can conclude that irrigation water is the most important resource of groundwater recharge in this area, consequently, it should be integrated into relevant hydrological models as the main source of groundwater recharge.     

Multi‐scale modelling of land‐use change and river training effects on floods in the Rhine basin

Land‐use changes effects on floods are investigated by a multi‐scale modelling study, where runoff generation in catchments of different sizes, different land uses and morphological characteristics are simulated in a nested manner. The macro‐scale covers the Rhine basin (excluding the alpine part), the upper meso‐scale covers various tributaries of the Rhine and three lower meso‐scale study areas (100–500 km²) represent different characteristic land‐use patterns. The main innovation is the combination of models at different scales and at different levels of process representation in order to account for the complexity of land‐use change impacts for a large river basin. The results showed that the influence of land‐use on storm runoff generation is stronger for convective storm events with high precipitation intensities than for long advective storms with low intensities. The simulated flood increase at the lower meso‐scale for a scenario of rather strong urbanization is in the order of 0 and 4% for advective rainfall events, and 10–30% for convective rain storms with a return period of 2–10 years. Convective storm events, however, are of hardly any relevance for the formation of floods in the large river basins of Central Europe, because the extent of convective rainstorms is restricted to local occurrence. Due to the dominance of advective precipitation for macro‐scale flooding, limited water retention capacity of antecedent wet soils and superposition of flood waves from different tributaries, the land‐use change effects at the macro‐scale are even smaller, for example at Cologne (catchment area 100 000 km²), land‐use change effects may result in not more than 1–5 cm water level of the Rhine. Water retention measures in polders along the Upper and Lower Rhine yield flood peak attenuation along the Rhine all the way down to the Dutch border between 1 and 15 cm. Copyright © 2007 John Wiley & Sons, Ltd.     

巢湖流域土地利用变化对雨洪调蓄能力的影响

为探究土地利用结构变化对雨洪调蓄能力的影响,以1980—2020年巢湖流域的土地利用数据和土壤数据为基础,采用GIS和SCS模型相结合的方法,分析了不同时期不同降雨尺度下巢湖流域径流产生及分布情况。结果表明：1980—2020年巢湖流域土地利用变化主要表现为建设用地的增加及耕地和林地的减少;流域土地利用综合指数持续增长,其中高强度土地利用区面积从127 km²增长到了1 624 km²。1980—2020年渗透性差的地区从1 706.0 km²增加到了2 398.1 km²,以城市区域扩张为主。2020年相较于1980年,在不同土地利用条件下,相同降雨量时径流量明显增大,且主要在巢湖流域的合肥地区,而在增加降雨量时,径流量的增加幅度逐渐减小,在不同降雨量条件下(日降雨量为50、100、250 mm)径流量分别增大了6.11%、2.61%和0.96%。因此可以得出土地利用变化是导致径流量变化的主要因素,降雨量是次要因素。研究结果可为巢湖流域城市规划及城市雨洪风险管理提供参考。