Passive diffusion sampling of sulfur dioxide in India: Impact assessment on arid areas

Environmental constraints have drastically limited options of sustainable development and have severely offset many developmental schemes. In this paper, possibilities of acidic deposition, as a counter measure of desertification, are analyzed. Seasonal data of ambient sulfur dioxide, pH of rain water and soil acidity are collected for over an year and analyzed. Arid environment of surrounding areas of Delhi is considered and analyzed. Though ambient sulfur deposition is well below critical level, it might not be truly indicative of plant survival in arid areas. Results may be useful in arid area afforestation, and polluting industries relocation, which holds tremendous potential vis-à-vis sustainable development.     

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.     

中国干旱和半干旱带的10年际演变特征

利用Thornthwaite的干湿分类函数,对近100年中国干旱和半干旱区界限的10年际变动特征进行了分析.结果发现：近50年,在东北中部和华北北部,干旱和半干旱边界呈波动式东移,有明显向东扩展的趋势;在华北南部和陕西南部,半干旱边界也呈波动式南扩,其中陕西南部半干旱边界向南扩展的范围最大.近100年,10年际的干旱和半干旱边界也呈波动式摆动且存在向东和向南扩展的趋势,但在华北南部与东北中部两个地区以20世纪20年代前后干旱和半干旱的范围最大、最强.干旱和半干旱分界线的位置变化与区域升温和降水减少密切相关.     

Development of a three‐dimensional watershed modelling system for water cycle in the middle part of the Heihe rivershed,in the west of China

A three‐dimensional numerical modelling system is developed to study transformation processes of water resources in alluvial fan and river basin along the middle reaches of the Heihe River Basin, Northwest China, an arid and semi‐arid region. Integrating land utilization, remote sensing and geographic information systems, we have developed a numerical modelling system that can be used to quantify the effects of land use and anthropogenic activities on the groundwater system as well as to investigate the interaction between surface water and groundwater. Various hydraulic measurements are used to identify and calibrate the hydraulic boundary conditions and spatial distributions of hydraulic parameters. In the modelling study, various water exchanges and human effects on the watershed system are considered. These include water exchange between surface water and groundwater, groundwater pumping, lateral water recharges from mountain areas, land utilization, and infiltration and evaporation in the irrigation and non‐irrigation areas. The modelling system provides a quantitative method to describe spatial and temporal distributions and transformations between various water resources, and it has application to other watersheds in arid and semi‐arid areas. Copyright © 2011 John Wiley & Sons, Ltd.     

Quantitative analysis of the driving factors for groundwater resource changes in arid irrigated areas

How to quantify the impact of climate change and human activities on groundwater is not only a hot topic of current research but also a key point of water resource management in arid irrigated areas. Therefore, this paper analyzes the changes in the trends of land use, climate, and groundwater extraction in the Yanqi Basin in recent years and uses the distributed hydrological model MIKE-SHE to quantitatively analyze the impacts of these three factors on groundwater resources. The results show that: 1. The Nash coefficients of the simulated and observed groundwater levels during the verification period are 0.84, 0.79 and 0.76; the correlation coefficient between the simulated and observed soil moisture is 0.86. Although there are some uncertainties in the simulation, the results prove that the model can be used to simulate arid irrigated areas. 2. The effects of these three factors on groundwater levels are 5, 12.5 and 82.5%, respectively, and have caused the regional average groundwater level to decrease by a maximum of 0.07, 0.23 and 1.79 m, respectively. The effects of these three factors on the interactions between surface water and groundwater were 7.04, 3.63 and 89.33%. Groundwater extraction has become the main influencing factor of regional groundwater resources changes due to its more direct influence. 3. The influence of groundwater extraction has a strong spatial distribution characteristic and 10% of the study area has been greatly impacted by the groundwater extraction. Base on the above results, integrating multidisciplinary knowledge to establish the relationship between ecological environment and groundwater changes can provide strategies for the sustainable development of groundwater.     

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。     

Tracing ground water input to base flow using sulfate (S, O) isotopes

Sulfate (S and O) isotopes used in conjunction with sulfate concentration provide a tracer for ground water contributions to base flow. They are particularly useful in areas where rock sources of contrasting S isotope character are juxtaposed, where water chemistry or H and O isotopes fail to distinguish water sources, and in arid areas where rain water contributions to base flow are minimal. Sonoita Creek basin in southern Arizona, where evaporite and igneous sources of sulfur are commonly juxtaposed, serves as an example. Base flow in Sonoita Creek is a mixture of three ground water sources: A, basin ground water with sulfate resembling that from Permian evaporite; B, ground water from the Patagonia Mountains; and C, ground water associated with Temporal Gulch. B and C contain sulfate like that of acid rock drainage in the region but differ in sulfate content. Source A contributes 50% to 70%, with the remainder equally divided between B and C during the base flow seasons. The proportion of B generally increases downstream. The proportion of A is greatest under drought conditions.     

渭河断陷盆地及邻区环境剪应力场及其与震源参数关系研究

利用陕西数字地震台网的数字地震资料研究了渭河断陷盆地及邻区的震源参数和环境剪应力场, 结果表明该地区地壳内环境剪应力处于较低水平, 平均值为12.7×10⁵ Pa, 并据此分析了该地区的地震活动性, 建立并探讨了环境剪应力与震级M_L、 地震矩M₀、 矩震级M_W的关系, 讨论了环境剪应力与震源深度间的关系。     

Some features of the arid area variations over India: 1871–1984

Spatial variability of the annual rainfall over drier regions of India is studied by examining the variations in the arid areas. A long period (1871–1984) arid area series has been prepared for the entire country, including the two broad subregions of North India and Peninsular India, using annual rainfall data from 306 well distributed stations. Following an objectively determined criterion based on rainfall amount alone, the yearly area under arid conditions is obtained by totalling areas which received annual rainfall totals less than 560 mm. The interannual variability of the arid area series is large and its distribution is highly right-skewed, demonstrating large spatial variations in the annual rainfall over India. Statistical tests do not suggest any significant long-term trend in the arid area series, but persistently low values of the arid area after 1941 are noteworthy. Implications for the study of risk analysis and assessment of drought and desertification processes are discussed.     

云南山地地震地质灾害对河流综合开发的影响

概述了云南河流的地质构造背景、地震活动及其震害一般特征；分析了云南河流主要干支流的地震地质环境，云南的河流径流面积的83.3%处在Ⅶ度及以上地震烈度区，已勘测出的近200处河流干支流水电站站址的绝大多数处在Ⅶ度及以上地震烈度设防区；对云南河流综合开发可持续发展中减轻地震地质灾害的工作提出了几点建议。     

腾冲火山区某些地震学参数特征

测定了腾冲火山区地震震中位置和震源深度,对火山区及附近的震源深度、地震时距曲线和地震波速度等地震学参数特征作了分析。结果表明,腾冲火山区地震震源深度相对较小,向周围地区逐渐增大,震源深度分布的低值区,又是环境剪应力场的值分布区。腾冲火山区Ｐ、Ｓ波平均速度,明显比外围地区小,腾冲火山区存在低速区。这些地震学参数分布的差异,一方面反映出地区作为火山区的固有特征及其地域分布的大小,同时也揭示出腾冲火山在     

Chronology and paleoenvironmental interpretation of talus flatiron sequences in a sub‐humid mountainous area: Tremp Depression,Spanish Pyrenees

Talus flatirons are debris‐covered relict slopes, disconnected from the source area, which are relatively common in arid and semi‐arid areas. Talus flatiron sequences record the alternation of accumulation and incision phases. These chronosequences may be used for infer temporal changes in the morphogenetic processes acting on the slopes as well as information on the local paleoclimatic history. Talus flatiron sequences developed in the Tremp Depression, eastern Spanish Pyrenees, are analysed from the geomorphological, chronological and paleoenvironmental perspective. The two groups of relict slopes differentiated by means of detailed geomorphological mapping have been dated by optically stimulated luminescence (OSL) and radiocarbon dating at 25–20 kyr (S3) and 5·4–1·7 cal kyr (S2). The talus flatiron group S3 is correlated with a fluvial terrace of the Noguera Pallaresa River (c. 23 kyr bp ). The comparison of the ages obtained in the Tremp Depression with chronologies published for talus flatiron sequences in semi‐arid areas and other paleoclimatic proxies suggests that the aggradation phases in the slopes occurred during periods with higher humidity and vegetation cover. The chronological differences observed between semi‐arid Spain and the Tremp Depression may be partly related to the more humid climate of the latter mountain area. Copyright © 2013 John Wiley & Sons, Ltd.     

Palaeoclimate and groundwater evolution in Africa—implications for adaptation and management

Abstract

Groundwaters of known age contained in major aquifer systems in the African sedimentary basins enable low-resolution (±1000 year) characteristics of past climates to be determined, specifically palaeo-temperature, air mass origins, humid/arid transitions and rainfall intensity. Results from both northern and southern Africa indicate the predominance of a westerly Atlantic air flow during the Late Pleistocene. Greater aridity during the Last Glacial Maximum (LGM) is recorded over most of northern Africa by the absence of dated groundwaters. An intensification of the African monsoon during the Early Holocene is apparent from isotopically light groundwaters found, in particular, over Sudan. Maximum cooling around the LGM of 5–7°C is recorded in the noble gas recharge temperatures from Africa. Modern recharge can be readily identified from the chemical and isotopic signatures (Cl, δ¹⁸O and ³H) in the unsaturated zone and in shallow groundwaters. The results indicate the non-renewability of many groundwater sources now being exploited across the arid and semi-arid regions of Africa. Extreme events in the past, noted from the groundwater record, may have lessons and implications for adapting to future climate change. Small but finite amounts of renewable groundwater may be estimated using chloride mass balance and other tracer techniques. These renewable waters form the basis of sustainable development in areas such as the Sahel. Based on the field evidence of water scarcity, new approaches are needed in management and education to adapt to the current limited resources in the face of changing climates.     

Semi‐Arid Aquifer Responses to Forest Restoration Treatments and Climate Change

The purpose of this study was to develop an interpretive groundwater‐flow model to assess the impacts that planned forest restoration treatments and anticipated climate change will have on large regional, deep (>400 m), semi‐arid aquifers. Simulations were conducted to examine how tree basal area reductions impact groundwater recharge from historic conditions to 2099. Novel spatial analyses were conducted to determine areas and rates of potential increases in groundwater recharge. Changes in recharge were applied to the model by identifying zones of basal area reduction from planned forest restoration treatments and applying recharge‐change factors to these zones. Over a 10‐year period of forest restoration treatment, a 2.8% increase in recharge to one adjacent groundwater basin (the Verde Valley sub‐basin) was estimated, compared to conditions that existed from 2000 to 2005. However, this increase in recharge was assumed to quickly decline after treatment due to regrowth of vegetation and forest underbrush and their associated increased evapotranspiration. Furthermore, simulated increases in groundwater recharge were masked by decreases in water levels, stream baseflow, and groundwater storage resulting from surface water diversions and groundwater pumping. These results indicate that there is an imbalance between water supply and demand in this regional, semi‐arid aquifer. Current water management practices may not be sustainable into the far future and comprehensive action should be taken to minimize this water budget imbalance.     

A review of aridity and groundwater

Surface hydrological studies are seen as inadequate in hyperarid and arid areas to provide reliable estimates of recharge. In most such areas surface discharges are not present so that assessments of groundwater resources are dependent upon ground interpretation and denied the flow control found in assessments elsewhere. Groundwater models show that gradients are sustained by long-term dewatering and very small amounts of modern indirect recharge. Recharge indications are well within the error of a hydrological balance. Discharges appear equally small. The development of groundwater in arid areas frequently faces problems of salination due to recycling of irrigation water and rising groundwater heads. Abstraction is often inadequately managed so that uncontrolled mining of groundwater occurs. The advantage that groundwater has, however, is that it offers staged development and staged appraisal.     

The impacts of human activities on the water–land environment of the Shiyang River basin,an arid region in northwest China / Les impacts des activités humaines sur l’environnement pédo-hydrologique du bassin de la Rivière Shiyang,une région aride du nord-ouest de la Chine

Abstract

Abstract The Shiyang River basin is a typical interior river basin that faces water shortage and environmental deterioration in the arid northwest of China. Due to its arid climate, limited water resources and some inappropriate water-related human activities, the area has developed serious loss of vegetation, and gradual soil salinization and desertification, which have greatly impeded the sustainable development of agriculture and life in this region. In this paper, the impacts of human activities on the water–soil environment in Shiyang River basin are analysed in terms of precipitation, runoff in branches of the river, inflow into lower reaches, water conveyance efficiency of the canal system and irrigation water use efficiency in the field, replenishment and exploitation of groundwater resources, soil salinization, vegetation cover and the speed of desertification. The results show that human activities and global climate change have no significant influence on the precipitation, but the total annual runoff in eight branch rivers showed a significant decrease over the years. The proportion of water use in the upper and middle reaches compared to the lower reach was increased from 1:0.57 in the 1960s, to 1:0.27 in the 1970s and 1:0.09 in the 1990s. A reduction of about 74% in the river inflow to the lower reaches and a 15-m drop in the groundwater table have occurred during the last four decades. Strategies for improving the water–soil environment of the basin, such as the protection of the water resources of the Qilian Mountains, sustainable use of water resources, maintenance of the balance between land and water resources, development of water-saving agriculture, diverting of water from other rivers and control of soil desertification, are proposed. The objective of this paper is to provide guidelines for reconstruction of the sustainable water management and development of agriculture in this region.     

Hydrograph and unit hydrograph derivation in arid regions

Arid and semi‐arid regions expose special hydrological features that are distinctive from humid areas. Unfortunately, humid‐region hydrological empirical formulations are used directly in the arid and semi‐arid regions without care about the basic assumptions. During any storm rainfall in arid regions, rainfall, infiltration and runoff components of the hydrological cycle have impacts on water resources. The basis of the methodology presented in this paper is the ratio of runoff increment to rainfall increment during an infinitesimally small time duration. This is the definition of runoff coefficient for the same infinitesimal time duration. The ratio is obtained through rational, physical and mathematical combination of hydrological thinking and then integrated with the classical infiltration equation for the hydrograph determination. The parameters of the methodology are explained and their empirical estimations are presented. The methodology works for rainfall and runoff from ungauged watersheds where infiltration measurement can be performed. The comparison of the new approach with different classical approaches, such as the rational formula and Soil Conservation Service method, are presented in detail. Its application is performed for two wadis within the Kingdom of Saudi Arabia. Copyright © 2006 John Wiley & Sons, Ltd.     

Assessment of CHADFDM satellite-based input dataset for the groundwater recharge estimation in arid and data scarce regions

Aquifer natural recharge estimations are a prerequisite for understanding hydrologic systems and sustainable water resources management. As meteorological data series collection is difficult in arid and semiarid areas, satellite products have recently become an alternative for water resources studies. A daily groundwater recharge estimation in the NW part of the Lake Chad Basin, using a soil–plant-atmosphere model (VisualBALAN), from ground- and satellite-based meteorological input dataset for non-irrigated and irrigated land and for the 2005–2014 period is presented. Average annual values were 284 mm and 30°C for precipitation and temperature in ground-based gauge stations. For the satellite-model-based Lake Chad Basin Flood and Drought Monitor System platform (CHADFDM), average annual precipitation and temperature were 417 mm and 29°C, respectively. Uncertainties derived from satellite data measurement could account for the rainfall difference. The estimated mean annual aquifer recharge was always higher from satellite- than ground-based data, with differences up to 46% for dryland and 23% in irrigated areas. Recharge response to rainfall events was very variable and results were very sensitive to: wilting point, field capacity and curve number for runoff estimation. Obtained results provide plausible recharge values beyond the uncertainty related to data input and modelling approach. This work prevents on the important deviations in recharge estimation from weighted-ensemble satellite-based data, informing in decision making to both stakeholders and policy makers.