Application of SWAT Model to the Olifants Basin: Calibration, Validation and Uncertainty Analysis

The application of the Soil and Water Assessment Tool (SWAT) to the Olifants Basin in South Africa was the focus of our study with emphasis on calibration, validation and uncertainty analysis. The Basin was discretized into 23 sub-basins and 226 Hydrologic Response Units (HRUs) using 3 arc second (90 m × 90 m) pixel resolution SRTM DEM with stream gauge B7H015 as the Basin outlet. Observed stream flow data at B7H015 were used for model calibration (1988-2001) and validation (2002-2013) using the split sample approach. Relative global sensitivity analysis using SUFI-2 algorithm was used to determine sensitive parameters to stream flow for calibration of the model. Performance efficiency of the Olifants SWAT model was assessed using Nash-Sutcliffe (NSE), coefficient of determination (R2), Percent Bias (PBIAS) and Root Mean Square Error-Observation Standard deviation Ratio (RSR). Sensitivity analysis revealed in decreasing order of significance, runoff curve number (CN2), alpha bank factor (ALPHA_BNK), soil evaporation compensation factor (ESCO), soil available water capacity (SOIL_AWC, mm H2O/mm soil), groundwater delay (GW_ DELAY, days) and groundwater “revap” coefficient (GW_REVAP) to be the most sensitive parameters to stream flow. Analysis of the model during the calibration period gave the following statistics;NSE = 0.88;R2 = 0.89;PBIAS = -11.49%;RSR = 0.34. On the other hand, statistics during the validation period were NSE = 0.67;R2 = 0.79;PBIAS = -20.69%;RSR = 0.57. The observed statistics indicate the applicability of the SWAT model in simulating the hydrology of the Olifants Basin and therefore can be used as a Decision Support Tool (DST) by water managers and other relevant decisions making bodies to influence policy directions on the management of watershed processes especially water resources.

Hydrologic Response of the Climatic Change Based on SWAT Model in Beijiang River Basin

[ Objective] The research aimed to establish SWAT distributed hydrologic model and analyze influence of the climatic change on runoff in Beijiang River basin. [ Method] Beijiang River basin as research object, SWAT model was used to simulate runoff in basin. Monthly water flow in Shijiao station from 1961 to 1980 was used to determine model parameter, while monthly water flow from 1981 to 1990 was used to verify. Setting 15 kinds of climate change scenarios, SWAT model was used to simulate influence of the future climatic change on runoff in Beijiang River basin. [Result] Simulated accuracy of the SWAT model was high, and it could be used to simulate runoff in Beijiang River basin. Under the situation of in- variable rainfall, temperature rise made that evaporation capacity increased, and runoff depth decreased. When temperature unchanged, rainfall increase made that evaporation capacity and runoff depth increased somewhat. [ Conclusion] The research could provide reference basis for water re- source management in Beijiang River basin.

Application of SWAT Model to Non-point Source Pollution in Xincai River Basin

[Objective]The study aimed to simulate the production and transportation process of surface runoff,sediment and non-point source pollution in Xincai River basin based on SWAT model.[Method]On the basis of analyzing the principles of SWAT model,the correlative parameters of runoff,sediment and water quality were calibrated,then the spatial and temporal distribution of runoff,sediment and non-point source pollutants in Xincai River basin were studied by using SWAT model.[Result]The results of calibration and validation showed that SWAT model was reasonable and available,and it can be used to simulate the non-point source pollution of Xincai River basin.The simulation results revealed that the load of sediment and various pollutants was the highest in the rainy year,followed by the normal year,while it was the minimum in the dry year,indicating that the production of sediment and non-point source pollutants was closely related to annual runoff.[Conclusion]The research could provide scientific references for the prevention of non-point source pollution in a basin.

Modeling Stream Flow Using SWAT Model in the Bina River Basin, India

Understanding watershed runoff processes is critical for planning effective soil and water management practices and efficiently utilize available water resources. The main objective of this study was to investigate the performance of the Soil and Water Assessment Tool (SWAT) to simulate streamflow from the Bina basin in the Madhya Pradesh state of India. The SWAT model was calibrated and validated on a daily and monthly basis using historical streamflow and weather data from the Bina basin. The Sequential Uncertainty Fitting (SUFI-2) technique in the SWAT? Calibration and Uncertainty Procedures (SWAT-CUP) program was used to assess model uncertainties. The SWAT model performed “satisfactory” and “very good” in simulating streamflow at daily and monthly time steps, respectively. Model calibration results showed that coefficients of determination (R2) values were 0.66 and 0.96;while Nash-Sutcliffe (NSE) values were 0.65 and 0.94 for daily and monthly simulations, respectively. The R2 values of daily and monthly simulations during model validation were 0.65 and 0.72, respectively while the respective NSE values were 0.58 and 0.72. This study demonstrated that the SWAT model could be effectively used to simulate streamflow in the Bina river basin.

基于SWAT模型的武强溪流域非点源污染关键源区界定与控制策略

随着点源污染的控制与处理技术日趋完善,非点源污染成为重要的水污染源。武强溪作为流入千岛湖的第二大支流,量化武强溪流域非点源污染负荷,解析非点源污染时空分布特征,提出适合削减武强溪流域污染物的最佳管理措施(best management practices,BMPs)对千岛湖水污染高效治理至关重要。该研究基于土壤水分评估工具(Soil and water assessment tool,SWAT)分析了武强溪流域径流量、总氮输出负荷量的时空分布特征,探究了不同管理措施及组合的削减效果,提出了武强溪流域非点源污染针对性的治理措施。结果表明:1)SWAT模型对于武强溪流域径流量和总氮输出负荷量的模拟具有较好的适用性,径流量校准期和验证期的决定系数(coefficient of determination,R^(2))分别为0.86、0.97,纳什系数(nash-sutcliffe coefficient,NSE)分别为0.83、0.96,百分比偏差(percent bias,PBIAS)分别为15.8%、-6.3%,总氮校准期和验证期的决定系数分别为0.87、0.74,纳什系数分别为0.63、0.66,百分比偏差分别为31.6%、21.2%;2)该流域径流量和总氮负荷主要集中在3—7月,分别占全年输出量的71.67%和75.76%。综合考虑氮的来源和流失途径,将耕地和林地面积占比大、坡度陡的子流域设置为总氮的关键污染源区。考虑调整化肥施用量/配方、改变耕作方式和设置植被缓冲带等削减非点源污染的手段,进行总氮输出负荷削减效率的情景模拟,表明10 m植被缓冲带是减少总氮输出负荷的最佳单一控制策略,总氮削减率可达到69.90%;实施综合管理措施对总氮的污染削减效果更佳,10 m植被缓冲带与施肥量减少20%可使总氮削减率达到74.79%。研究结果可为千岛湖水质管理与控制提供理论基础。

基于SWAT模型的滏阳河流域断流河道复流研究

针对滏阳河流域断流河道生态修复的问题,为了实现断流河道尽可能恢复有水时间并且恢复基本生态功能的目标,基于节水措施和调水工程现状,通过建立滏阳河流域SWAT(soil and water assessment tool)水文模型,在模型中设置不同补水水量、补水方式的生态补水情景,分析不同情景下断流河道断面的径流量变化和恢复有水天数,并结合生态流量评价标准评价不同情景的河流生态恢复效果。结果表明:滏阳河流域邯郸断面在节水情景和调水情景中恢复河流生态效果较好,在通过上游节水措施和补充年调水1.00×10^(8)m^(3)/a的情景下,可以达到5—10月恢复有水184 d、恢复径流量3486.7×10^(4)m^(3)/a的目标;年内恢复径流峰值在8月中旬,并且河道年均径流量可以恢复到“好”等级的生态流量标准。滏阳河下游邢台断面在节水情景和调水情景下恢复径流量较少,河道有水天数不达标,需要在上游节水条件下补充外来调水水量1.50×10^(8)m^(3)/a来达到恢复年有水天数304 d、恢复径流量1906.5×10^(4)m^(3)/a的目标,年内恢复径流峰值分别在3月中旬和8月中旬;并且在达到恢复有水目标的情景下邢台断面仅达到“一般”等级的生态流量标准,需要考虑增加调水水量进行分时段单点位补水的补水方案。

基于区域水平衡理论和SWAT模型的沁河流域水收支平衡演变分析

基于区域水平衡理论和SWAT模型,提出了分布式水收支平衡模型的构建思路及水收支平衡计算方法,对人类活动和未来气候变化情景下的沁河流域水收支平衡状况进行模拟,并通过皮尔逊相关系数和Mann-Kendall检验方法分析了水收支平衡的关键影响要素及其演变规律。结果表明:2010—2016年沁河流域蓄水总量呈下降趋势,降水量及出口径流量为沁河流域水收支平衡相对关键的影响要素;未来多气候情景下蓄水总量呈上升趋势,多年平均降水量及出口径流量两个关键影响要素的总体变化情况与辐射强迫水平呈正相关关系;典型气候情景SSP2-4.5下降水量及出口径流量在2037—2041年、2061—2063年可能存在突变。

基于SWAT和PLUS模型的窟野河流域径流对土地利用变化的响应及预测

[目的]为揭示窟野河流域径流对土地利用变化的响应,并预测未来径流变化。[方法]以窟野河流域为研究区,基于SWAT和PLUS模型,通过2000年、2005年、2010年、2015年、2020年和预测得到的自然发展情景下2025年、2030年7期土地利用数据,定量分析径流在不同土地利用情景下的变化。[结果](1)SWAT模型率定期和验证期的R 2和NS均>0.7;PLUS模型总体精度为0.8774,Kappa系数为0.8021,2个模型在窟野河流域适用性较好;(2)2000—2020年,窟野河流域林地、建设用地面积分别增加102.92,600.90 km 2,耕地、草地、水域和未利用地分别减少277.15,366.25,40.44,19.98 km 2;(3)窟野河流域年平均径流深整体呈现“上游低,下游高,西部低,东部高”的空间分布格局;(4)在保证其他输入数据不变的情况下,改变土地利用数据,情景分析结果表明,林地、草地面积减少会促进径流,建设用地面积增加同样会促进径流;(5)自然发展情景下,2025年和2030年窟野河流域土地利用空间分布格局未发生显著变化,仍以耕地和草地为主,年平均径流量较2020年分别增加3.21%,5.00%。[结论]土地利用与径流变化关系密切,情景分析角度下,林地、草地对径流起抑制作用,建设用地对径流起促进作用。未来自然发展情景下,随土地利用变化,径流呈增加态势,研究结果可为窟野河流域的土地利用结构优化和水土资源的合理规划提供科学依据。

不同降水驱动的SWAT模型参数不确定性研究

以抚河流域与黑河流域为研究区,应用4种降水产品(CMORPH CMA、CMFD、CMADS、MSWEP)驱动SWAT模型模拟日流量,评估4种降水产品在湿润区与干旱区的适用性;使用自适应降维评估法选出流域的敏感参数,并进行一致性检验。结果表明:抚河流域4种降水产品的纳什效率系数(NSE)均在0.70以上,其中CMORPH CMA和CMADS的NSE均能达到0.82;黑河流域CMORPH CMA和CMADS的NSE大于等于0.76,而CMFD和MSWEP的NSE分别为0.72和0.74。抚河流域4种降水产品具有相同的敏感参数;黑河流域CMORPH CMA和CMADS有相同的6个敏感参数,而CMFD和MSWEP则分别有5个和8个敏感参数。4种降水产品在湿润流域和干旱流域都能得到较好的应用效果,但是CMORPH CMA和CMADS的模拟效果要优于CMFD和MSWEP。不同的降水输入也会对模型参数敏感性分析的结果产生影响,当降水表现越接近时,所筛选的敏感性参数也越相似。

Contribution of Agro-Hydrological Modeling in the Evaluation of Water Availability of an Ungauged Basin Reservoir in Côte d’Ivoire: Case of the Loka Reservoir in Bouaké

The city of Bouaké, the second biggest city of Côte d’Ivoire, experienced a water shortage in 2018 that lasted four months due to the drying up of the Loka reservoir, which supplies two-thirds of the city. The challenge of the Loka reservoir is that it is located in an ungauged basin where very few hydrological studies have been carried out, despite the recurrent problems of access to drinking water. In the purpose to better understand the phenomena that caused this temporary drying of the dam, the methodology implemented was based on agro-hydrological modeling with SWAT using a regionalization technique of a nearby watershed. The model performance was assessed using three statistical indices (the Nash-Sutcliffe coefficient (NS), the coefficient of determination (R2) and the percentage of bias (PBIAS)) and the visual appreciation of hydrographs for monthly series. The statistical indices appear satisfactory with a NS and R2 ≥ 0.6 both for calibration and validation, and a PBIAS of -11.2 and -3.8 respectively for calibration and validation. The hydrological modeling of Loka basin has shown the impact of climate change already reported by some authors as well as anthropization. Thus, while the reservoir records a decrease in its water volume estimated at 384,604 m3 each year, the water demand undergoes an increase of 122,033 m3 per year.

基于SWAT模型的渠江流域径流侵蚀功率时空规律分析

探明流域径流侵蚀功率的演变规律对重点侵蚀区识别和土壤侵蚀防治至关重要。以嘉陵江右岸支流渠江流域为研究区,基于SWAT模型模拟计算流域径流侵蚀功率,分析其时空分布特征与空间尺度效应,并通过聚类分析、相关性分析揭示其对流域气象、地形、土壤等因素的关系。结果表明:渠江流域年尺度的径流侵蚀功率大于季尺度,其中第3季度为土壤侵蚀重点防治时段;全年和第3季度的多年平均径流侵蚀功率均呈现出北部大南部小、西部大东部小、上游大下游小的空间分布特征;渠江干流与其支流大通江的多年平均径流侵蚀功率和流域控制面积之间均呈幂指数关系,且其变化规律存在空间阈值,在年尺度干流和大通江的阈值面积分别为8549.4和8504.4 km^(2),在第3季度干流和大通江的阈值面积分别为4834.9和6223.5 km^(2);气象因子、地形因子和流域形态因子为渠江流域径流侵蚀功率的主要影响因素。研究结果可为制订渠江流域土壤侵蚀治理方案提供决策依据。

基于SWAT的乌伦古河流域气候和土地利用变化对径流和总磷的影响

[目的]定量探讨气候和土地利用变化对径流和总磷负荷的影响,为新疆乌伦古河流域未来水土资源的合理开发利用及水污染的防控提供科学参考。[方法]通过构建SWAT分布式水文模型,采用情景分析法设定6种不同的变化情景,预测了流域在变化环境下的径流和总磷负荷。[结果]径流和总磷在率定期和验证期的决定系数R^(2)和纳什系数E_(ns)均达到0.75以上,构建的SWAT模型在乌伦古河流域径流和总磷负荷变化的模拟中具有较好的适用性。气候和土地利用变化共同影响下,年均径流量分别上升0.22 m^(3)/s,5.14 m^(3)/s,S_(4)情景年均总磷负荷下降894.5 t,S_(5)情景增加7.41 t。气候变化影响方面,径流量与降水变化呈正相关,降水变化是乌伦古河流域径流变化的主要驱动因素,而总磷负荷与气温和降水变化均呈正相关,但降水对总磷负荷的影响更显著;土地利用变化影响方面,径流和总磷与土地利用变化均呈负相关关系,土地利用变化是总磷负荷增加的主要影响因素之一。[结论]气候和土地利用变化对新疆乌伦古河流域的径流和总磷负荷的产生分别具有促进和抑制作用,未来面临降水增多与水体污染问题时,需同时考虑气候和土地利用变化的影响来制定相应政策。

基于SWAT的沁河流域水压力指数计算及生态脆弱性分析

生态脆弱性是综合反映流域生态系统健康水平的重要属性,而水资源是维持流域生态系统健康和可持续发展的关键因素。因此,从水资源领域评估流域生态脆弱性并分析其时空变化特征对于应对流域水资源短缺压力和改善流域生态系统健康水平具有重要的研究价值。以沁河流域为研究对象,构建流域SWAT模型,引入水压力计算公式,从蒸散发量的角度,量化分析沁河流域2010-2016年生态脆弱性的时间变化和空间分布特征。结果表明:①SWAT模型经过率定与验证后,纳什系数E NS和相关系数R 2均符合模型精度标准,表明该模型在沁河流域具有良好的适用性。②流域年际水压力指数值随时间递减,表明沁河流域生态脆弱性及生态系统状态逐年好转,蒸散发量是主要影响因素。③流域水压力指数年内变化大,本年度12月到次年度2月的生态脆弱性较强;结合相关研究结果,认为降水和冰雪天气是主要影响因素。④流域整体生态脆弱性状况逐年改善,但流域内部生态脆弱性空间差异化呈现扩大趋势。

Hydrological Evaluation with SWAT Model and Numerical Weather Prediction for Flash Flood Warning System in Thailand

Flash floods are a natural disaster that occurs annually, especially in the mountainous terrain and steep slopes of northern Thailand. The current flood forecasting systems and tools are available but have low accuracy and efficiency. The numbers of rainfall and runoff stations are less, because the access to the station area is difficult. Additionally, the operation and maintenance costs are high. Hydrological modeling of a SWAT （Soil and Water Assessment Tool） was used in this study with the application of three days weather forecast from the NWP （numerical weather prediction）, which provided temperature, relative humidity, rainfall, sunshine and wind speed. The data from NWP and SWAT were used to simulate the runoff from the Nan River in the last 10 years （2000-2010）. It was found that the simulated flow rate for the main streams using data from NWP were higher than the observations. At the N64 and Nl stations, the ratios of the maximum simulated flow rate to the observations were equal to 108% and 118%, respectively. However, for the tributaries, it was found that the simulated flow rate using NWP data was lower than the observations, but, it was still within the acceptable range of not greater than 20%,6. At N65, D090201 and D090203 stations, the ratio of the maximum simulated flow rate were 90.0%, 83.0% and 86.0%, respectively. This was due to the rainfall from the NWP model being greater than the measured rainfall. The NWP rainfall was distributed all over the area while the rainfall data from the measurements were obtained from specific points. Therefore, the rain from the NWP model is very useful especially for the watershed areas without rain gauge stations. In summary, the data from the NWP can be used with the SWAT model and provides relatively sound results despite the value for the main river being slightly higher than the observed data. Consequently, the output can be used to create a flood map for flash flood warning in the area.

基于SWAT模型的马莲河流域地下水资源评价

为全面了解及合理开发利用地下水资源,选取马莲河流域为研究对象,通过构建SWAT分布式水文模型,采用SUFI-2算法进行参数敏感性分析、参数确定和模型验证,对流域出口水文站雨落萍站2006-2019年的逐月径流量进行模拟.模型验证期R2和纳什效率系数分别为0.75和0.64,满足要求.对马莲河流域地下水潜水层储量、天然补给量、可开采量进行估算.流域地下水储量空间分布差异明显,2006-2019年储量减少3.79×10^(9)m^(3),损失量较大,且潜水层储量与潜水层厚度和地质构造状况有关.流域模拟期多年平均地下水径流模数为0.36 L/(s·km^(2)),多年平均天然补给量为2.29×10^(8)m^(3),多年平均可开采量为1.37×10^(8)m^(3).

基于水文学法和SWAT模型的北川河流域生态需水量分析

为确定北川河流域生态需水量,采用线性趋势法、Mann-Kendall检验法、Spearman检验法分析了北川河流域1959—2013年径流变化趋势,并采用Pettitt检验、滑动t检验、滑动F检验和累积距平法综合诊断径流突变点,根据Tennant法和改进的年内同频率展布法确定的生态流量过程外包线计算河道内生态需水量,并基于SWAT模型计算了河道外生态需水量。结果表明:SWAT模型在研究区具有适用性,模型性能符合“好”的标准,SWAT模型模拟的降水量和蒸发量总体呈现增加趋势,产水量呈现减少趋势;北川河流域桥头水文站径流量呈现减少趋势,年平均减少率为0.104 m^(3)/s,径流突变点为1990年;北川河流域河道内生态需水量为2.95亿m^(3),河道外生态需水量为9.95亿~10.85亿m^(3),生态总需水量为12.90亿~13.80亿m^(3)。

基于SWAT模型的蓝绿水短缺指数计算与风险评价

为了降低沁河流域水资源短缺风险,以沁河流域为研究对象,基于所构建SWAT模型的输出结果,估算2010—2016年沁河流域蓝绿水资源量,利用蓝绿水足迹和可利用蓝绿水资源量计算蓝绿水短缺指数,并划分4个蓝绿水短缺风险等级,定量评估沁河流域蓝绿水短缺状况。结果显示:1)沁河流域多年平均蓝水资源量为9.1亿m^(3),占水资源总量的12.0%;多年平均绿水资源量为66.9亿m^(3),占水资源总量的88.0%,说明沁河流域水资源大部分为绿水资源;2)年尺度下沁河大部分子流域的蓝水短缺指数大于1.0,蓝水短缺风险等级为较大风险,其中下游地区的焦作市蓝水短缺问题尤为严重;3)年尺度下沁河各子流域的绿水短缺指数呈现一定差异性,大部分子流域多年平均绿水短缺指数在0.5~1.0范围内,绿水短缺面临中度风险,总体而言,绿水短缺风险低于蓝水短缺风险。基于蓝绿水短缺指数分析,提出应对沁河流域水安全风险的措施建议。

SWAT+模型在郪江流域的适用性探究

为评估SWAT+模型在四川省内流域模拟的适用性,通过构建SWAT、SWAT+模型,探究SWAT+模型在郪江流域的径流、总磷非点源模拟适用性。结果表明,两款模型表现出了良好的径流模拟效果,R2和纳什效率系数均达到0.6以上,SWAT+模型表现出更好的适用性。两款模型的总磷模拟效果合格,SWAT+模型对总磷模拟的R2和纳什效率系数均比SWAT略高,郪江流域2015年月均总磷污染负荷强度约为0.93~1.59 kg/(ha·月),总体呈现上游低下游高的趋势。SWAT+在流域配置、输入文件格式、土地利用及管理等方面有较大提升,且能够刻画面状水系,在建设有水库、池塘、闸坝的研究区域内建模更精准,但目前存在河道生成效率低的缺点。总体而言,SWAT+模型在郪江流域表现出较好的适用性,有望凭借其优质的用户体验和良好的模拟效果取代SWAT模型。

基于SWAT模型祖厉河流域非点源污染优先管理区识别研究

为识别祖厉河流域非点源污染优先管理区,基于SWAT模型选取黄河一级支流祖厉河流域为研究对象,研究首先模拟出流域非点源总氮污染负荷空间分布情况,以及分别从年际和月际变化角度分析流域总氮负荷变化;并考虑子流域上下游关系及河道对于污染物的滞留作用,以流域黄河汇入口为水质影响监测点,根据子流域相对于整个流域的总氮污染强度,进行非点源污染优先管理区的划分。结果表明:SWAT模型在祖厉河流域适用,利用SWAT-CUP软件针对径流和水质的模拟值进行参数率定,其纳什效率系数均高于0.5。由模拟结果可以得出,各子流域总氮负荷相差较大,位于上游的子流域总氮负荷较小,而负荷较大的子流域,主要分布在河流出口处;自2001-2022年的20年间,整个流域的总氮负荷的变化趋势与年降水量的变化大致相同;并且季节性变化明显,在夏季总氮负荷最高。根据总氮污染强度,将子流域划分为三类污染优先管理区,通过对比发现,在20年间流域中需要对非点源污染优先管理的子流域,大致沿祖厉河上游的苦水河主河道由南致北纵向分布。该成果可为祖厉河流域非点源污染治理及生态修复与保护工作提供参考。

基于SWAT模型的鄱阳湖流域典型年份蓝绿水时空变化特征研究

采用SWAT模型分析1970—2018年鄱阳湖流域典型年份蓝水绿水资源量的时空分布差异特征,并对典型年份绿水系数的变化进行评析。结果表明:典型年份蓝绿水资源量均是最涝年最多、最旱年最少、平水年适中。蓝水量的变化趋势较大,绿水量的变化比较稳定,其中绿水流是绿水量的主体部分,绿水储仅占极小部分;蓝水量呈现由东北向西南减少的趋势,与降水量的空间分布基本保持一致,绿水资源不仅与降水等气候条件有关,还与人类活动和下垫面的性质有关;流域绿水系数并不高,最旱年绿水系数最高,为45.42%,最涝年绿水系数最低,为33.91%,平水年为38.75%,表明蓝水资源在鄱阳湖流域的水资源构成中占主导地位,并且绿水系数的空间分布与降水量的空间分布趋势呈现出明显的反差。