Improving watershed management practices in humid regions

In many parts of the world, watershed management practices have been extremely effective. However, implementation of soil and water conservation technologies in the humid African highlands, while beneficial in the short term, were remarkably unsuccessful in the long term. Insights from community knowledge perspectives have revealed that alternative methods are needed. Although conservation practices are designed to conserve water in semi‐arid areas, safely draining excess water is needed in humid areas. The objective of this paper is to review current watershed management approaches used in humid regions as exemplified by those used in Ethiopian highlands and then based on these findings propose more effective practices. Although current government sponsored practices primarily protect the hillsides, direct run‐off is generated from areas that become saturated on valley bottoms near rivers and on specific parts of the hillsides with degraded soils (or with highly permeable surface soils) and with perched water tables on slowly permeable horizons at shallow depths. In these areas, direct run‐off is increasing with deforestation and the soil degradation, demanding additional drainage ways that evolve in the form of gullies. Therefore, watershed management interventions for erosion control should prioritize revegetation of degraded areas, increasing sustainable infiltration, and rehabilitating gullies situated at saturated bottomlands.     

Identification of physical processes inherent in artificial neural network rainfall runoff models

The emergence of artificial neural network (ANN) technology has provided many promising results in the field of hydrology and water resources simulation. However, one of the major criticisms of ANN hydrologic models is that they do not consider/explain the underlying physical processes in a watershed, resulting in them being labelled as black‐box models. This paper discusses a research study conducted in order to examine whether or not the physical processes in a watershed are inherent in a trained ANN rainfall‐runoff model. The investigation is based on analysing definite statistical measures of strength of relationship between the disintegrated hidden neuron responses of an ANN model and its input variables, as well as various deterministic components of a conceptual rainfall‐runoff model. The approach is illustrated by presenting a case study for the Kentucky River watershed. The results suggest that the distributed structure of the ANN is able to capture certain physical behaviour of the rainfall‐runoff process. The results demonstrate that the hidden neurons in the ANN rainfall‐runoff model approximate various components of the hydrologic system, such as infiltration, base flow, and delayed and quick surface flow, etc., and represent the rising limb and different portions of the falling limb of a flow hydrograph. Copyright © 2004 John Wiley & Sons, Ltd.     

流域综合管理方法与技术

流域作为一个具有明确边界的地理单元,流域以水为纽带,将上、中、下游组成一个普遍具有因果联系的复合生态系统,是实现资源和环境管理的最佳单元.流域综合管理已经被认为是实现资源利用和环境保护相协调的最佳途径.然而,由于流域综合管理涉及多学科,多部门,内容非常广泛.近年的流域管理还主要停留在一个目标.本文在流域模拟管理研究及实践的相关经验基础上,系统地讨论了流域综合管理实施方法、关键技术以及主要技术问题.     

Watershed science: Linking hydrological science with sustainable management of river basins

Over the past decades, a number of water sciences and management programs have been developed to better understand and manage the water cycles at multiple temporal and spatial scales for various purposes, such as ecohydrology,global hydrology, sociohydrology, supply management, demand management, and integrated water resources management(IWRM). At the same time, rapid advancements have also been taking place in tracing, mapping, remote sensing, machine learning, and modelling technologies in hydrological research. Despite those programs and advancements, a water crisis is intensifying globally. The missing link is effective interactions between the hydrological research and water resource management to support implementation of the UN Sustainable Development Goals(SDGs) at multiple spatial scales. Since the watershed is the natural unit for water resources management, watershed science offers the potential to bridge this missing link.This study first reviews the advances in hydrological research and water resources management, and then discusses issues and challenges facing the global water community. Subsequently, it describes the core components of watershed science:(1)hydrological analysis;(2) water-operation policies;(3) governance;(4) management and feedback. The framework takes into account water availability, water uses, and water quality; explicitly focuses on the storage, fluxes, and quality of the hydrological cycle; defines appropriate local water resource thresholds through incorporating the planetary boundary framework; and identifies specific actionable measures for water resources management. It provides a complementary approach to the existing water management programs in addressing the current global water crisis and achieving the UN SDGs.     

Impacts of climate change on the Qingjiang Watershed’s runoff change trend in China

Qingjiang River, the second largest tributary of the Yangtze River in Hubei Province, has taken on the important tasks for power generation and flood control in Hubei Province. The Qingjiang River watershed has a subtropical monsoon climate and, as a result, has dramatic diversity in its water resources. Recently, global warming and climate change have seriously affected the Qingjiang watershed’s integrated water resources management. In this article, general circulation model (GCM) and watershed hydrological models were applied to analyze the impacts of climate change on future runoff of Qingjiang Watershed. To couple the scale difference between GCM and watershed hydrological models, a statistical downscaling method based on the smooth support vector machine was used to downscale the GCM’s large-scale output. With the downscaled precipitation and evaporation, the Xin-anjiang hydrological model and HBV model were applied to predict the future runoff of Qingjiang Watershed under A2 and B2 scenarios. The preformance of the one-way coupling approach in simulating the hydrological impact of climate change in the Qingjiang watershed is evaluated, and the change trend of the future runoff of Qingjiang Watershed under the impacts of climate change is presented and discussed.     

Evaluating watershed service availability under future management and climate change scenarios in the Pangani Basin

Watershed services are the benefits people obtain from the flow of water through a watershed. While demand for such services is increasing in most parts of the world, supply is getting more insecure due to human impacts on ecosystems such as climate or land use change. Population and water management authorities therefore require information on the potential availability of watershed services in the future and the trade-offs involved.In this study, the Soil and Water Assessment Tool (SWAT) is used to model watershed service availability for future management and climate change scenarios in the East African Pangani Basin. In order to quantify actual “benefits”, SWAT2005 was slightly modified, calibrated and configured at the required spatial and temporal resolution so that simulated water resources and processes could be characterized based on their valuation by stakeholders and their accessibility. The calibrated model was then used to evaluate three management and three climate scenarios.The results show that by the year 2025, not primarily the physical availability of water, but access to water resources and efficiency of use represent the greatest challenges. Water to cover basic human needs is available at least 95% of time but must be made accessible to the population through investments in distribution infrastructure. Concerning the trade-off between agricultural use and hydropower production, there is virtually no potential for an increase in hydropower even if it is given priority. Agriculture will necessarily expand spatially as a result of population growth, and can even benefit from higher irrigation water availability per area unit, given improved irrigation efficiency and enforced regulation to ensure equitable distribution of available water. The decline in services from natural terrestrial ecosystems (e.g. charcoal, food), due to the expansion of agriculture, increases the vulnerability of residents who depend on such services mostly in times of drought. The expected impacts of climate change may contribute to an increase or decrease in watershed service availability, but are only marginal and much lower than management impacts up to the year 2025.     

中国东南丘陵山区水质良好水库现状与天目湖保护实践

东南丘陵山区是我国水库分布最为集中的区域之一,这些水库在保障区域供水安全方面具有极其重要的作用,应该优先保护.然而,水库水环境保护正面临丘陵山区开发强度持续增加,开发方式和空间布局不合理,氮、磷污染及富营养化趋势严峻,缺乏完善监测和管理体系等众多问题.本文以2000年以来天目湖水库保护实践过程为例,从库体水环境治理、流域污染物削减和综合管理3个方面介绍天目湖沙河水库保护的措施和成效,在此基础上提出良好湖库优先保护的建议:建立具有部门协调能力的水库管理机构,实行基于湖库水生态目标的水质目标管理,治理丘陵山区茶果园的面源污染,注重流域生态系统整体的恢复,禁止上游水源涵养区和临湖地带的开发,划定生态保护红线,明确禁止和限制的开发类型与规模,加强湖库及流域的监测和预警,开展必要的水库水体治理工程,并针对性地制定湖库管理条例.天目湖十几年的保护实践中有效地解决了流域开发与水库水质保护之间的矛盾,使天目湖水质由快速恶化转为稳步好转,为东南丘陵山区经济发展过程中水库的环境保护探索了一条道路.     

流域综合管理发展的历程、经验启示与展望

探索流域管理的理论与实践,不仅有助于理解流域演变的客观规律、提高管理效能,而且能为流域综合管理科学的逐步形成与完善以及流域综合管理实践提供有益参考.文章在总结回顾流域管理发展历程的基础上,着重分析流域管理发展的现状与问题,认为流域资源、环境与经济发展的综合协调与管理,建立行之有效的新型流域综合管理体制和管理机制,流域问题的跨学科综合研究与先进技术的应用等四个方面将是流域综合管理未来研究的主要趋势.     

Scenario-based assessment and management of water resources in mid-Himalayan micro-watersheds with limited data availability

Abstract

A conceptual hydrological water balance model has been developed and employed to assess the water availability in a mid-Himalayan watershed and analyse the dynamics of water supply and its utilization under different scenarios arising out of present and future developments. The model was calibrated and validated using daily runoff and rainfall data at different locations in the watershed. The water availability in streams and springs to meet the human, animal and crop requirements was assessed, and was found to vary in different quarters of the year with inequalities existing in different parts of the watershed. The model was successfully applied to analyse the impact of land-use changes and weather aberrations on water availability in the present and future scenarios. The drought scenarios are more critical in causing water scarcity in a given location, compared to the impact of land-use changes. The findings can be applied for assessing, planning and allocation of water resources among different sectors of water use in hilly areas and to make informed decisions during critical periods of water scarcity.     

Management of an aquifer with artificial recharge using water balance

Abstract

This study considers the management of an aquifer with artificial recharge whose water resources are mainly used for irrigation and where the irrigation return flows and natural discharge are considerable. These two variables are dependent on the use and increase of water resources. The interaction between some inflow and outflow variables is taken into account in the computation of the actual volume of water available, there being a pre-established artificial recharge of the aquifer. Conversely, the artificial recharge for a given water demand may be calculated. The most important inflow and outflow variables are used in an equation system (the water balance for each period of time) for these interactions and the total inflow and outflow. An iterative procedure is developed that solves the equation and with it the computation of the actual availability of water and storage.     

Assessing and regulating the impacts of climate change on water resources in the Heihe watershed on the Loess Plateau of China

Climate change can cause considerable changes in water resources and assessing the potential impacts can provide important information for regional sustainable development. The objectives were to evaluate the possible impacts of climate change during 2010-2039 on water resources (runoff, soil water content, and evapotranspiration) in the Heihe watershed on the Loess Plateau of China and to further explore adaptive measures to cope with the changes. Projections of four climate models (CCSR/NIES, CGCM2, CSIRO...     

Development of a polder module in the SWAT model: SWATpld for simulating polder areas in south‐eastern China

Polders are one of the most common artificial hydrological entities in the plain river network regions of China. Due to enclosed dikes, manual drainage, and irrigation intake operations, polders have had a significant impact on the hydrological processes of these areas. Distributed hydrological models are effective tools to understand and reproduce the hydrological processes of a watershed. To date, however, few models are able to simulate the drainage and irrigation intake interactions of polders at a watershed scale. This study develops a modified version of the Soil and Water Assessment Tool (SWAT) model, which is designed to better represent polders (SWATpld). The SWATpld model simulates drainage and irrigation intake processes by calculating the excess‐water storage in the inner rivers and irrigation schedule for paddy rice in the polder. Both SWAT and SWATpld models were tested for the Liyang watershed. SWATpld outperformed SWAT in simulating the daily discharge and intake of the experimental polder and predicting the monthly peak flow at the outlet of the Liyang watershed, which suggests that the modified model simulates the hydrological responses of the study watershed with polder operations more realistically than the original SWAT model does. Further evaluation at various locations and in various climate conditions would increase the confidence of this model.     

马湖水资源的初步分析

详细阐述了马湖的地理位置、湖盆形态、流域水系特征及湖区自然概况。从研究水资源的角度出发,实测了水下地形,并进行了湖水的水量平衡分析计算。分析湖水的理化特性,包括:水色、透明度、温度、溶解性气体、pH值、营养物质、矿化度和水型等,并根据其水资源特点,提出了开发和综合利用的措施。     

湖北牛山湖小型鱼类的群落结构及多样性

流域数据模型是流域特征的语义、行为和规则的表达,是进行集成流域模拟和管理的空间数据组织的重要内容．本文以长江三角洲太湖流域上游的西苕溪流域为例,将汇流单元分为自然流域、“大包围”、圩区三种形式,分别建立了各自内部的河湖网络关系,即山区由自然流域单元,内包含水库(或湖泊)、河流、水工点的树状河湖网络关系;平原区由人工汇流单元,内包含大包围、圩区、湖泊、湿地、河道、水工点的网状河湖网络关系,为建立适合我国的流域数据模型做了有益的探索．     

EROSION AND SEDIMENTATION PROBLEMS IN SOME ASIAN COUNTRIES

1 INTRODUCTIONFrom 1989 to 1993, as project managers of the UNDP/UNESCO project entitled Regional TrainingProgramme on Erosion and Sedimentation for Asia, the writers had the privilege of meeting manyoutstanding hydraulic engineers of this region and came to learn of some important erosion andsedimentation problems thereof. Some issues as noted by the writers are presented in the followingalong the some comments. These issues are mainly concerned with rivers. It should be stated tha…     

Soil seed bank composition and distribution on eroded slopes in the hill‐gully Loess Plateau region (China): influence on natural vegetation colonization

On the Chinese Loess Plateau, serious slope and gully erosion have caused a decrease in soil water capacity and fertility, which has resulted in vegetation degradation and a reduction in agricultural productivity. Great efforts have been made to restore vegetation to control soil erosion, but the efficiency of artificial revegetation is not satisfactory. Natural revegetation is an alternative. However, while soil seed banks are an essential source for natural revegetation, their composition and distribution on eroded slopes remains unknown. In addition, whether or not seed loss during soil erosion limits vegetation colonization is also unknown. In this work, soil seed bank composition and distribution were studied in three situations. Specifically, three main microsites were selected as sampling plots: fish‐scale pits, as artificial deposited micro‐topography; under tussocks, as trap microsites; and open areas, as eroded areas. Soil samples were collected at depths of 0–2 cm, 2–5 cm and 5–10 cm. The soil seed bank was identified using germination experiments, and a total of 34 species were identified. The dominant species in the soil seed bank were annual/biennial herbs with an average proportion more than 90% and density reaching 19,000 seeds m^‐2. The pioneer species Artemisia scoparia was especially abundant. The dominant later successional species, such as Lespedeza davurica, Artemisia giraldii, Artemisia gmelinii, Stipa bungeana and Bothriochloa ischcemum, were present in the soil at a density that ranged from 38 to 1355 seeds m^‐2. Compared with the eroded open areas, the fish‐scale pits retained a higher density of seeds, and the tussocks retained a larger number of species. However, there was no serious reduction of the soil seed bank in the erosion areas. The present study indicates that, on these eroded slopes, the soil seed bank is not the key factor limiting the colonization of natural vegetation. Copyright © 2011 John Wiley & Sons, Ltd.     

Lake Water Resources in the Asian Part of the Russian Federation

Water resources of lakes with natural and regulated hydrological regime are evaluated, and estimates are given to the water resources of artificial water bodies in three federal districts in the Asian part of RF (Ural, Siberian, and Far-Eastern) and the constituent entities of the Federation they contain. The estimates were made by a new procedure, incorporating up-to-date satellite data and functions of Google Earth project. In the Asian part of RF, ~3140000 natural water bodies were analyzed, including ~1170000 lakes >1 ha in area and ~6000 artificial water bodies. Lake water resources in the Asian part of RF amount to 24537 km³, of which ~96% are contained in Lake Baikal. Other 638 km³ are contained in artificial water bodies.     

不同尺度流域地表径流氮、磷浓度比较

选择太湖上游为研究对象,采集了1-400 km2不同尺度小流域产出径流TN、TP浓度实测数据,结合前期开展的地表坡面流人工暴雨实验监测结果,开展不同尺度流域水质监测对水体面源污染产出浓度估算影响的比较研究,探讨流域尺度之间入渗、汇流以及伴随的流域生态系统营养盐调节机制的差异．结果表明,流域监测尺度对土地利用面源污染产出浓度估算有较大影响．地表坡面流由于未经过流域汇流过程伴随的下渗滤过与吸附等过程,产出径流TN、TP浓度一般高于小流域．小流域林地生态系统具有较强的入渗机制、接近自然的生态沟谷汇流网络,对面源污染TN、TP有较强的削减作用．农业生态系统较弱的入渗机制、人工沟渠汇流网络对面源污染TN、TP的削减作用较弱．现代农业造成流域面源污染增加不仅仅是因为人类农业活动对流域局部土体及养分的改变,农业生态系统改变流域自然生态系统整体水文过程及营养盐调节机制也是面源污染增加的重要因素之一,恢复小尺度的生态沟谷网络系统对削减流域面源污染具有重要的意义．     

流域管理基本法则研究——以长江流域系统管理为例

流域是自然形成的水动力系统,流域管理是以水资源为中心的科学管理管理"是用法律、规范、条例、办法等来实现的,而流域是复杂的系统,具有整体性、动态性、耗散性, 同时它是人类赖以生存的资源环境.因此流域管理就应该顺应河流流水的动态变化.长江流域的管理是一项系统工程,应坚持以综合管理为根本、以科学预测为基础、以降低熵值为目标、以环境安全为核心.即在坚持整体综合全面统筹的前提下,其治理和开发必须以科学预测为基础,尤其是洪涝灾害的治理应该有中长期的灾害预测作为启动治理工程的根据;同时管理的目标是降低系统熵值以加大系统稳定性和有序性;还有长江流域管理的核心任务是流域环境安全,以保证流域经济、社会和生态的可持续发展.     

新疆平原沙漠区湖泊干缩现象的初步评价

对新疆平原沙漠区湖泊干缩现象作了初步评价,指出这一现象是干旱、半干旱地区农业灌溉和国民经济发展到一定规模时所必然产生的现象,因而可以视为正常。同时指出,平原区湖泊之存亡既取决于自然条件,更取决于社会经济发展的需要。现存湖泊资源的开发与保护,既要立足于生态环境价值论,也要立足于经济价值论。