Evaluation of a small basin water-harvesting system in the arid region of Jordan

The performance of a small runoff-basin water-harvesting system (negarim) was evaluated under a typical Mediterranean arid environment in Jordan. Rainfall, runoff, catchment area, soil water storage, and crop evapotranspiration were analyzed as elements of one system. Three micro-catchment areas (25, 50, and 75 m²) and three surface treatment methods (natural, plastic cover, and compaction) were used. Runoff efficiency was evaluated for 16 storms. Storage efficiency was evaluated for eight periods by monitoring soil water balance in the crop root zone. The overall efficiency of the water-harvesting system was determined as the ratio of the amount of water stored and used by the crop to the amount of rainfall received in the catchment area. The overall efficiency of the system varied from over 85% to as low as 7% depending on the size of the catchment and the root zone capacity. Gains in runoff improvement were lost when the soil moisture in the cultivated area was near field capacity. The required ratio of the catchment area to the cultivated area was found to be strongly related to the root zone storage capacity and the rate of consumptive use as well as rainfall-runoff characteristics.     

A GIS Based Design of Groundwater Level Monitoring Network Using Multi-Criteria Analysis and Geostatistical Method

Groundwater systems are dynamic and hence, an effective and optimally designed groundwater level (GWL) monitoring network is very essential to minimize monitoring, time and long term expenses. Groundwater scarcity is a big challenge in regions where excessive extraction takes place and GWL monitoring from observation wells (OWs) is the principal source of information. Hence, proper observation and management is necessary to ensure continual availability of water supplies. This study proposes a new and simplified approach using multi-criteria analysis (weighted overlay, analytical hierarchical process, fuzzy) and geostatistical (ordinary kriging) method to design GWL monitoring network of the Wainganga sub-basin, India. Several parameters considered for the analysis include command area (CA) and non command area (NCA), geology, geomorphologic unit, land use/land cover (LU/LC), lineament density, Groundwater level fluctuation (GWLF), recharge, slope and soil media. The study identifies representative or priority zones using multi-criteria analysis and optimum number of OW was determined within the representative zones using geostatistical method. Combination of two approaches helps overcome shortcomings of previously suggested methods of which analytical hierarchical process (AHP)-geostatistical approach gives more accurate results. Sensitivity analysis was carried out to identify importance of each parameter considered for analysis. The study concludes that minimum 80 wells are required for proper monitoring of GWL in the study area. It also reveals that a combination of these two approaches is effective and easy to implement in the regions where data availability is not constrained.     

基于分布式水文模拟的流域土壤水分时间稳定性分析

针对大范围地面土壤水监测会耗费大量人力物力等问题,为了获取密度较高同时又准确可靠的流域土壤水数据用于时间稳定性分析,寻找可以反映流域土壤水平均状况的代表性点,利用分布式水文土壤植被模型(DHSVM)模拟淮河黄泥庄水文站以上小流域293个采样网格上、中、下三层土壤含水量数据。结果显示:垂向方向上,黄泥庄流域土壤水分时间稳定性随深度递减;流域上层和中层具备时间稳定性特征的代表性点具有较高的一致性,易发生于流域主要土壤和植被类型覆盖区域,在此区域布设测点观测土壤水,可以更准确快速地捕获代表黄泥庄流域上层和中层平均土壤水分特征;采样点7、17和215可作为上、中层土壤的流域平均土壤水代表性点,利用它们预测流域土壤水平均值,可降低观测成本。研究成果可为流域土壤水监测方案设计提供参考。     

Optimal Sites Identification for Rainwater Harvesting in Northeastern Guatemala by Analytical Hierarchy Process

The Guatemala’s rural population have limited resources, high vulnerability to climate change, traditional agriculture practices and adversely affected by water scarcity. These problems engender the need for further economic development and imposed pressure on the existing water resources. In response, Rain Water Harvest (RWH) is the measure as an alternative source towards water shortage problem and a decrease in groundwater extraction. However, the identification of optimal sites for RWH is an important step to maximize the amount of water harvested and minimize the ecological impact. In this study, an Analytical Hierarchy Process (AHP) was used to determinate optimal sites using Geographic Information Systems (GIS) in order to integrate spatial information. Physical and socio-economic features were main decision criteria along with six sub-criteria: potential runoff; land use; soil texture; slope; distance from agricultural land; and distance from roads. In the investigation, several different criteria with different AHP structures were utilized to assess the flexibility of structures. The result maps with respect to different criteria and AHP structurs are overlaid in a systematic scheme to identify the most suitable site for RWH project. The results identified four sites as optimally suitable and eight as highly suitable. The total 424,070.81 m³ volume of water can be potentially harvested from these optimally and highly suitable sites. The study area comprised of 770.61 km² of Guatemala northeastern region and it is suggested that the RWH system for agriculture purpose should be promoted through government and multistakeholder co-operations as an alternative water resource.     

基于极化雷达的裸露地表土壤水分反演研究

为准确、快速提取大范围裸露地表土壤水分空间分布,以河套平原巴彦淖尔市杭锦后旗陕坝镇灌区土壤水分四极化精细模式雷达监测为例,研究基于RADARSAT-2数据土壤水分提取的技术与方法,选择AIEM模型作为研究区裸露地表土壤水分反演模型的基础,建立适合河套灌区裸露地表土壤水分微波散射的经验模型。应用经验模型对河套灌区地表水分进行反演研究并与实测数据进行相关性分析。结果表明极化组合VV-VH的相关程度高达0.931 1,经验模型能够满足土壤水分监测的需要,优于传统土壤水分分类方法,促进了极化微波遥感在土壤水分监测中的开拓应用。     

GIS多源数据图层叠置法研究山东省干旱分区

为揭示山东省干旱孕灾环境的自然背景和干旱空间分布格局,通过基于GIS的图层叠置方法对山东省干旱分布进行区域划分。首先根据山东省干旱成因选取降水量、土壤含水量、植被指数NDVI和气温4个干旱因子进行GIS栅格数据处理,得到相应的干旱因子图层;然后利用层次分析法确定各干旱因子的权重,把上述归一化后的4个干旱因子图层进行加权叠置,得到综合干旱因子图;最后,将综合干旱因子图与山东省高程分布图层进行叠加,得到山东省5个干旱分区,即鲁西北平原北部的农业重旱区、鲁西北平原的南部和胶莱平原农业轻旱区、胶东半岛较湿润区、鲁中南山地丘陵湿润区、山东南部沿海区域的平原湿润区,并提出了各分区的适宜干旱指标。该研究可为山东省干旱监测预警提供孕灾环境方面的理论支撑。     

Spatiotemporal Surface-Groundwater Interaction Simulation in South Florida

South Florida ecosystem is dictated by a large wetland, karst hydrogeology and extended coastal boundary with the Atlantic Ocean. The risks related to the ecosystem include: disruption of groundwater flow as a result of frequent sinkhole formation; flooding in urban areas as a result of the shallow water table; saltwater intrusion from the ocean; and excessive nutrient load to surficial water bodies and subsequently eutrophication because of the intensive utilization of wetlands for nutrient removal. Attempts to understand eco-hydrological processes primarily focus on extensive monitoring and use of distributed hydrological models. However, the relatively flat nature of the region and also the extended coastal boundary with the ocean, makes watershed-based approaches less realistic. A regional spatiotemporal groundwater level modeling approach was attempted using a Dynamic Factor Analysis (DFA) method. The daily water levels of 13 monitoring well sites from major hydrogeologic regions and different land uses were used to conduct the DFA analysis, and six dynamic factors were identified using minimum Akaike Information Criterion (AIC). Further exploratory analysis to relate the dynamic factors with physically attributable explanatory variables has helped to identify five of the major factors that govern the groundwater dynamics in south Florida. Three of the factors were attributable to the Lake Kissimmee water level in the north, Caloosahatchee River water level in the west, and Hillsboro canal in the east. The other two factors identified were the regional averaged rainfall and soil moisture. The spatiotemporal simulation involved interpolation of the loadings of the dynamic factors using an inverse distance weighted method and convoluting with the dynamic factors. The result has shown a good fit with the maximum RMSE of 0.12?m. Retrieval of rainfall, soil moisture, and surface water level from satellite imagery makes spatiotemporal modeling of the groundwater level achievable.     

Integrated Consideration of Quality and Quantity to Determine Regional Groundwater Monitoring Site in South Korea

As the purpose of the regional groundwater monitoring station is to observe both quality and the levels of groundwater in South Korea, it is most efficient and economical to establish the monitoring station at a site able to observe these two items simultaneously. A weighting and ranking method using GIS technology was used for the development of a site selection model. This model uses a land-use type of target area with regard to quality and a lineament length density with regard to quantity. It was shown that this weighting and ranking method is appropriate and convenient for selecting a monitoring site because it proposes the relative importance and priority of groundwater monitoring for each site. Additionally, if this method is used together with the other method like an analytical hierarchy process (AHP) method, the optimal and specific monitoring site can be easily selected and the additional field investigation can be reduced.     

Comparative Simulation of GIS-Based Rainwater Management Solutions

Rain Water Harvesting (RWH) as a solution for sustainable rainwater management is the focus of this research. To locate the potential sites for RWH, multi-criteria analysis following analytical hierarchy process using land-use/landcover, slope, drainage density, and runoff depth has been performed. By introducing continuous soil moisture accounting procedure in the globally used SCS-CN method, discrepancies in computed runoff values have been assessed. To appraise the usefulness of revised Soil Moisture Accounting (SMA) -enhanced SCS-CN models, a number of modifications have been compared. The models’ performance has been evaluated using R², Root Mean Square Error (RMSE), Nash Sutcliffe Efficiency (NSE), Percent BIAS (PBIAS) statistical indicators, and Rank Grading System (RGS) and the best has been selected to calculate the runoff depth for RWH potential zones. The resultant suitability map classifies Gurriala catchment into three suitability zones. 33.8% of the total area has been found as least suitable, comprised mainly of forest, residential land, and water bodies, while 46.8% and 19.4% of the area is recognized as moderately suitable and high suitable respectively. Selected suitable sites have been further classified into suitability zones for enhanced RWH structures and runoff volume contributed by each RWH structure has been computed. The total runoff potential of the area is 22.47 MCM that is enough to fulfill the water demands of suburban areas as a most inexpensive solution.

     

区域土壤含水率遥感监测分析方法研究进展

土壤水分是陆地表面参数化的一个关键变量。遥感技术为大面积动态监测土壤水分提供了可能。简述了热惯量法、作物缺水指数法、植被指数距平法、微波遥感法、高光谱法五种目前为止比较成熟和广泛应用的土壤水分遥感监测方法和模型,并进行了优缺点分析。     

非饱和残积土土-水特性研究及基质吸力估算

残积土在我国南方分布十分广泛,是工程建设及地质灾害评估中主要遇到的土体之一。非饱和状态下,残积土边坡土体的工程性质不仅取决于土的组成、结构和应力状态,还与土中的吸力密切相关;土-水特征曲线表达了土体中含水量与吸力的关系,是非饱和土研究的重要内容之一。选取福建省有典型代表的凝灰质砂砾岩残积土、凝灰岩残积土以及花岗斑岩残积土3种类型土作为试验土样,测定土样完整的脱湿、吸湿循环过程的土-水特征曲线。鉴于基质吸力测量困难,在Barden非饱和土分类方法的基础上,通过分析具有实际工程意义的含水量情况(饱和度介于50%~90%),总结出的利用饱和度预测基质吸力的简易方法具有针对性和实用性。     

宇宙射线中子法在荒漠草原土壤水测量中的应用

选择典型荒漠草原为研究区,开展了宇宙射线中子法在其土壤含水量监测中的适用性分析研究。利用宇宙射线中子传感器(CRS)对典型荒漠草原土壤含水量进行连续监测,将监测结果与时域反射仪(TDR)测量结果进行比对,分析了二者测量结果的一致性,并对比两种土壤水测量方法对降雨响应的灵敏度。结果显示,CRS与TDR测量结果的一致性较高;TDR对降雨事件的反应不够灵敏,而CRS不仅能够快速对降雨做出响应,而且能够清晰显示出不同降雨量条件下土壤含水量的不同变幅。因此,宇宙射线中子法可以较准确地测量荒漠草原的土壤含水量及其动态变化,能够为畜牧管理决策提供依据。     

森林集水区水文效应的研究

对油松山杨林水区和经济过抚育间伐后的集水区进行了分析的结果表明：水文过程线主要取决于降雨过程，产流特点是径流系数小，洪水含沙量低。一方面两集水区的水文特片值均较小，充分体现了森林良好的水源涵养作用；另一方面，两集水区在洪水起伏量，水文响应，单位面积洪量方面差异不大，表明适量间伐对集水区水文状况的影响很小。本文针对森林集水区沟道洪水径流量与降雨量，降雨强度，前期降雨量，土壤水分条件关系密切的特点，建     

基于区域特征相似度的微波土壤水分反演结果可信度评价

微波遥感反演土壤水分的精度评价,一般通过选取有限数量采样点的地表实测土壤水分数据与反演值进行比较,实际上只能反映局部采样区的反演精度。本文提出了微波反演土壤水分中一种可以评价整个研究区反演土壤水分可信程度的方法。首先选择采样区的实测土壤水分数据和地表粗糙度数据,通过多元回归统计拟合得到土壤水分反演经验方程,对整个研究区进行土壤水分反演;然后从TM和SAR数据中通过反演和提取,选择影响土壤水分的10个因子(土壤湿度、地表温度、NDVI、土壤质地指数、地形指数、雷达入射角以及Landsat TM的b3、b4、b5、b7共4个波段),采用主成分分析法(PCA)筛选提取主成分,将前3个主成分合成为RGB影像;再使用分水岭算法分割包含前3个主成分的RGB影像,得到一幅分割区域图;最后计算各分割区域的6维特征向量(土壤湿度、地表温度、NDVI、土壤质地指数、地形指数、雷达入射角)与反演时选择采样区的特征向量间的马氏距离,得到区域特征相似度数据集,基于该数据集计算反演结果可信度。以此为基础,利用2008年甘肃黑河地区的ENVISAT ASAR双极化数据(VV、VH)和实测土壤水分数据进行土壤水分反演并评价反演结果的可信度,同时使用反演区域中多个采样区土壤水分实测数据和确定系数(R2)评价反演精度,对比可信度和R2,表明提出的反演可信度可以有效反映土壤水分反演精度。     

洛阳市垃圾填埋场场址适宜性评价及优选

为了选取洛阳市未来适合的垃圾填埋场,采用层次分析法对洛阳市5个拟选垃圾填埋场地进行了适宜性评价,评价时将城市规划、交通运输、环境保护、环境地质等条件作为评价的具体标准,通过场地评价影响因子定权重和采用多目标线性加权函数的数学模型计算各拟选场地的综合评分。结果表明,拟选场地东沟、泰山庙沟的适宜性等级为较适宜,潘沟、后五龙沟的适宜性等级为勉强适宜,安贺沟为非适宜场地。适宜性评价为洛阳市未来垃圾填埋场的优选提供了科学依据。     

衡水市土壤墒情变化规律及预报分析

依据衡水水文实验站2010-2012年土壤含水率观测资料,分析衡水地区土壤墒情特点,研究代表区域的土壤墒情变化规律。利用实际观测资料,分析计算土壤消退系数K值,并拟合增墒计算经验公式,建立了退墒及增墒预报方案,并利用2013年资料进行了验证,经评定,两方案的预报精度均达100%,达到甲级预报标准。对合理指导农作物实施灌溉,保障农业生产,具有重要的意义。     

Mapping Field Surface Soil Moisture for Hydrological Modeling

Soil moisture is a major control variable on hydrological processes both at the storm event scale and in the long term. The aggregate effect on the mean water balance over an area can be quantified successfully using hydrological models. However, determination of soil moisture distribution for semi or fully distributed models is difficult. In some types of landscape, the distribution of soil moisture is dictated by topography, in others by soil characteristics, or by a combination of both. Distribution of area-average soil moisture according to the likely effect of local topography is presented and tested. The heterogeneity of the soil moisture is described by the Xinanjiang distribution, commonly used to describe the natural spatial heterogeneity of the landscape. This distribution is then mapped onto the terrain using topographic index to locate the wettest and driest areas. Soil moisture data from Bilecik-Kurukavak catchments are used to test the method. Cumulative density functions (CDF) for soil moisture data obtained from 68 locations in eight different dates and corresponding topographic index values are obtained. From these functions the deviations of the wet values from the mean soil moisture are observed as positive and larger compared to the dry values. The temporal stability of moisture patterns was studied in order to identify optimal sampling points for field-average soil moisture. Such points were identified by calculating their deviation over time from field average. Topographic data were analyzed to determine if these sampling points could be identified from time-invariant data.     

Suspended sediment load estimation in an ungauged river in south‐eastern Australia

Soil erosion poses a significant threat to river health as well as the sustainability of soil resources. Management of this issue requires catchment‐specific data to be developed; however, many large catchments are poor in terms of hydrological and sediment transport data. Regional scale (thousands of square kilometres), computer‐based modelling methods are a way to generate such data. This study aims to apply the SedNet model to estimate a sediment budget for a 575 km², ungauged, agricultural catchment of south‐eastern Australia. The model results are then compared with field measured erosion rates for the catchment, in order to assess the sustainability of soil loss and redistribution across the catchment. SedNet estimated average suspended sediment concentrations between 70 and 120 mg/L, under conditions deemed most representative of the river. These model estimates were comparable with monitoring data, showing suspended sediment concentrations between 30 and 350 mg/L. It was found that soil loss and redistribution across the catchment is low; however, the estimated base sediment loads indicate that river health may be negatively impacted by this. SedNet accurately represented current catchment and river conditions and provided a reliable estimation of sediment yield, demonstrating the ability to estimate sediment loss and redistribution across data‐poor catchments using a multifaceted modelling approach. Methodologies, such as the one presented here, offer the ability to better assess the impacts of erosion on sediment loads to develop strategies to effectively manage excess suspended sediment.     

SWR水分监测系统在黄土高填方工程中的应用研究

黄土高填方工程的变形与稳定性受土体含水率的变化影响大。为了应用SWR水分监测系统对黄土高填方工程的土体含水率变化进行监测,研发了插针式SWR土壤水分传感器的探井埋设工艺,在采用烘干法获得实际体积含水率与对应输出电压数据的基础上,探讨了将SWR土壤水分传感器输出电压进行归一化处理后与体积含水率进行回归分析建立标定模型的方法。结果表明,探井埋设方法可将SWR土壤水分传感器准确可靠地安装就位,SWR土壤水分传感器经标定后,观测精度和个体间的互换性得到显著提高,能够准确反映土体中水分的动态变化规律。     

Riparian wetlands for enhancing the self-purification capacity of streams.

Best Management Practices (BMPs) are increasingly used to restore river water quality but design guidance is limited. An alternative approach to remediating diffuse pollution loads is to identify the most polluting high flows from pollutographs and hydrographs and spill these flows into riparian treatment wetlands for treatment before drainage back into the watercourse. The approach is demonstrated for two contrasting catchments in Scotland impacted by diffuse pollution. The Caw Burn receives industrial estate drainage with high suspended solids, hydrocarbons, BOD and ammoniacal-nitrogen concentrations. Applying the proposed design criteria demonstrated that the existing retrofit BMP system at the site is undersized (4950 m2) compared to the required wetland area (11,800 m2), but accommodating the additional area is likely to be expensive. The second case-study is Brighouse Bay where bathing waters are impacted by faecal indicator organisms derived primarily from livestock runoff. In this catchment the riparian wetland area required to retain runoff so that E. coli bacteria would die-off to concentrations below bathing water standards was estimated to be 3-6ha (0.5-1% of catchment area). Further refinement and testing of the design approach is required, including consideration of other factors such as vegetation type, ownership and maintenance, to develop a more holistic approach to river restoration.