Land use change increases flood hazard: a multi-modelling approach to assess change in flood characteristics driven by socio-economic land use change scenarios

Natural Hazards - We analysed in the work how change in land use/land cover influences on flood characteristics (frequency and magnitude) using a model inter-comparison approach, statistical...     

长武黄土塬区土地利用变化对潜水补给的影响

通过长武黄土塬区不同土地利用方式下深剖面土壤水分的长期定位监测以及氢氧稳定同位素示踪技术的使用,分析了该区域土地利用变化对地下潜水补给的影响。结果表明:① 降水补给地下水过程中存在着活塞流和优先流两种机制,由活塞流补给的地下水量,以休闲地居高,低产农田次之,最后是高产农田;② 随着该区域农田生产力大幅提升以及大面积农田转换为果园,地下水活塞流补给量逐年减少,加之地下水开采量增加,导致地下水位逐年下降,年均降幅达0.3 m;③ 同位素证据表明,目前长武塬区地下水补给以优先流形式为主。为了实现黄土塬区潜水资源的有效补给与可持续利用,需要合理调控土地利用结构,保持适度生产力水平。     

Land use change

Despite decades of interest by geographers in patterns and processes of land use change, the data base for such studies is at best fragmentary. In the absence of an adequate land inventory, it is difficult to see how an effective land planning and allocation system can be devised to meet future social, economic and ecological needs. It is argued that a more comprehensive system for monitoring land use change is required, and the role and accuracy of remote sensing in providing a land use survey base is assessed.     

Climate change impacts on a Mediterranean river and the associated interactions with the adjacent coastal area

The Spercheios river basin—coastal marine area is a complex natural and interdependent ecosystem, highly affected by human activities and interventions. Such sensitive systems are even more vulnerable to alterations of the hydrological cycle components and it is likely to be rapidly and severely affected by climate change. In order to examine the climate change impacts on water resources of the study area, the interaction between the hydrology of the river basin and the hydrodynamic of the coastal marine area was examined using two models. Based on the results, although the irrigation needs decrease for the years 2050 and 2100 due to corresponding decrease in cultivated areas, temperature increase and precipitation decrease are both expected to influence the water resources of the Spercheios river basin, which will directly affect the Maliakos Gulf hydrodynamics. The necessity to adopt a holistic approach which will treat river basins and coastal marine areas as an integrated whole, with regard to environmental, socio-economic and political framework, is evident.     

Evaluation of groundwater quality for irrigation and drinking using GIS and geostatistics in a peri-urban area of Delhi, India

Intensive agriculture by indiscriminate use of agrochemicals, sewage water, and polluted drain water has posed a serious threat to groundwater quality in some peri-urban areas of Delhi like Najafgarh block. The objective of the study was to determine the groundwater quality and to map their spatial variation in terms of suitability for irrigation and drinking purpose. Ordinary kriging method was used for preparation of thematic maps of groundwater quality parameters such as electrical conductivity, sodium adsorption ratio, bicarbonate, magnesium/calcium ratio, total dissolved solids, chloride, nitrate and hardness. Exponential semivariogram model was best fitted for all quality parameters except chloride and hardness, where spherical model fitted best. Pollution level was highest at south and south-eastern part of the study area. Better quality groundwater may be expected at the northern and western part. High salinity was due to high chloride concentration in the groundwater. Nitrate pollution level was found to be very alarming and need immediate interventions. High dissolved solids and hardness made the groundwater unsuitable for drinking. There were negligible sodium and bicarbonate hazard in the study area. The groundwater quality index was devised to analyse the combined impact of different quality parameters on irrigation and drinking purposes. The irrigation water quality index and drinking water quality index distribution maps delineated an area of 47.29 and 6.54 km² suitable for irrigation and drinking, respectively. These safe zones were found as a small strip along the northern boundary and a very small pocket at the western side of the study area.     

神东矿区地下水变化观测与分析研究

针对西部大规模高强度煤炭开采对地下水的影响,利用神东矿区约1 500 km²区域的200余个钻孔的长期观测结果,研究了超大综采工作面开采工艺对地下水系统的影响规律,地下水流场变化与基岩和含水层空间分布的关系。研究表明,超大综采工作面开采形成了地下水\     

Stochastic groundwater modeling of a sedimentary aquifer: evaluation of the impacts of abstraction scenarios under conditions of reduced recharge

A transient finite difference groundwater flow model has been calibrated for the Nasia sub-catchment of the White Volta Basin. This model has been validated through a stochastic parameter randomization process and used to evaluate the impacts of groundwater abstraction scenarios on resource sustainability in the basin. A total of 1500 equally likely model realizations of the same terrain based on 1500 equally likely combinations of the data of the key aquifer input parameters were calibrated and used for the scenario analysis. This was done to evaluate model non-uniqueness arising from uncertainties in the key aquifer parameters especially hydraulic conductivity and recharge by comparing the realizations and statistically determining the degree to which they differ from each other. Parameter standard deviations, computed from the calibrated data of the key parameters of hydraulic conductivity and recharge, were used as a yardstick for evaluating model non-uniqueness. All model realizations suggest horizontal hydraulic conductivity estimates in the range of 0.03–78.4 m/day, although over 70 % of the area has values in the range of 0.03–14 m/day. Low standard deviations of the horizontal hydraulic conductivity estimates from the 1500 solutions suggest that this range adequately reflects the properties of the material in the terrain. Lateral groundwater inflows and outflows appear to constitute significant components of the groundwater budgets in the terrain, although estimated direct vertical recharge from precipitation amounts to about 7 % of annual precipitation. High potential for groundwater development has been suggested in the simulations, corroborating earlier estimates of groundwater recharge. Simulation of groundwater abstraction scenarios suggests that the domain can sustain abstraction rates of up to 200 % of the current estimated abstraction rates of 12,960 m³/day under the current recharge rates. Decreasing groundwater recharge by 10 % over a 20-year period will not significantly alter the results of this abstraction scenario. However, increasing abstraction rates by 300 % over the period with decreasing recharge by 10 % will lead to drastic drawdowns in the hydraulic head over the entire terrain by up to 6 m and could cause reversals of flow in most parts of the terrain.     

Climate change impacts on groundwater resources: modelled deficits in a chalky aquifer,Geer basin,Belgium

An integrated hydrological model (MOHISE) was developed in order to study the impact of climate change on the hydrological cycle in representative water basins in Belgium. This model considers most hydrological processes in a physically consistent way, more particularly groundwater flows which are modelled using a spatially distributed, finite-element approach. Thanks to this accurate numerical tool, after detailed calibration and validation, quantitative interpretations can be drawn from the groundwater model results. Considering IPCC climate change scenarios, the integrated approach was applied to evaluate the impact of climate change on the water cycle in the Geer basin in Belgium. The groundwater model is described in detail, and results are discussed in terms of climate change impact on the evolution of groundwater levels and groundwater reserves. From the modelling application on the Geer basin, it appears that, on a pluri-annual basis, most tested scenarios predict a decrease in groundwater levels and reserves in relation to variations in climatic conditions. However, for this aquifer, the tested scenarios show no enhancement of the seasonal changes in groundwater levels.

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Resumen Se ha desarrollado un modelo hidrológico integrado (MOHISE) para estudiar el impacto del cambio climático en el ciclo hidrológico de cuencas representativas en Bélgica. Este modelo considera todos los procesos hidrológicos de forma coherente, especialmente en relación con los flujos de aguas subterráneas, que son modelados por medio de un enfoque de elementos finitos espacialmente distribuidos. Gracias a esta herramienta numérica precisa, y tras una calibración y validación detalladas, se puede obtener interpretaciones cuantitativas de los resultados del modelo del acuífero. Considerando escenarios de cambio climático IPCC, se ha aplicado el enfoque integrado a la evaluación del impacto de dicho cambio climático en el ciclo hidrológico de la cuenca del Geer. Se describe los detalles y resultados del modelo de las aguas subterráneas en términos del impacto del cambio climático en la evolución de las reservas de los acuíferos. Los resultados preliminares indican que es posible esperar déficits de aguas subterráneas en un futuro en Bélgica.

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Résumé Un modèle hydrologique intégré (MOHISE) a été développé afin détudier limpact du changement climatique sur le cycle hydrologique de bassins versants représentatifs de Belgique. Ce modèle prend en compte tous les processus hydrologiques dune manière physiquement consistante, plus particulièrement les écoulements souterrains qui sont modélisés par une approche spatialement distribuée aux éléments finis. Grâce à cet outil numérique précis, après une calibration et une validation détaillées, des interprétations quantitatives peuvent être réalisées à partir des résultats du modèle de nappe. Considérant des scénarios de changements climatiques de lIPCC, lapproche intégrée a été appliquée pour évaluer limpact du changement climatique sur le cycle de leau du bassin du Geer en Belgique. Le modèle de nappe est décrit en détail et les résultats sont discutés en terme dimpact du changement climatique sur lévolution des réserves souterraines. Les premiers résultats indiquent que des déficits deau souterraine peuvent apparaître dans le futur en Belgique.

     

Groundwater withdrawal impacts in a karst area

During a 3000-gpm pump test on a groundwater supply well in Augusta County, Virginia, residential properties were impacted. The impacts included lowered farm pond water levels, development of a sinkhole, and water level decrease in residential wells. A study was performed to assess whether a lower design yield was possible with minimal impacts on adjacent property. This study included a 48-h 1500-gpm pump test that evaluated impacts due to: (1) sinkhole development and potential damage to homes, (2) loss of water in residential wells, and (3) water-quality degradation. Spring flows, residential well levels, survey monuments, and water quality were monitored. Groundwater and surface water testing included inorganic water-quality parameters and microbiological parameters. The latter included particulate analyses,Giardia cysts, and coliforms, which were used to evaluate the connection between groundwater and local surface waterbodies. Although results of the study indicated a low potential for structural damage due to future sinkhole activity, it showed that the water quality of some residential wells might be degraded. Because particulate analyses confirmed that groundwater into the supply well is under the direct influence of surface water, it was recommended that certain residents be placed on an alternate water supply prior to production pumping and that filtration be provided for the well in accordance with the Surface Water Treatment Rule. A mitigation plan was implemented. This plan included crack surveys, a long-term settlement station monitoring program, and limitation of the groundwater withdrawal rate to 1.0 million gallons per day (mgd) and maximum production rate to 1500 gpm.     

伊通河流域土地利用变化及其生态响应

通过遥感影像解译获取伊通河流域1986、1996、2005和2017年土地利用数据,采用土地利用动态模型、土地利用度和生态系统服务价值等方法,研究伊通河流域土地利用变化特征及其生态响应。研究结果表明,耕地、城镇建筑用地和林地是伊通河流域主要的土地利用类型,1986—2017年间,研究区土地利用综合动态度降低,土地利用度上升,土地利用结构趋于稳定。在31年间,生态系统服务价值整体下降33.97%,林地、草地、湿地和水域面积的减小导致生态系统服务价值显著降低。     

Potential impacts of climate change on groundwater levels on the Kerdi-Shirazi plain,Iran

It is important to predict how groundwater levels in an aquifer will respond to various climate change scenarios to effectively plan for how groundwater resources will be used in the future. Due to the overuse of groundwater resources and the multi-year drought in the Kerdi-Shirazi plain in Iran, some land subsidence and a drop in groundwater levels has taken place, and without active management, further degradation of the groundwater resource is possible under predicted future climate change scenarios in the country. To determine the potential impacts of climate change on groundwater levels in the region, the groundwater model GMS was coupled with the atmospheric circulation model HADCM3 using scenarios A1B, A2 and B1 for the period 2016–2030. The results of the climate modelling suggest that the Kerdi-Shirazi plain will experience an increase in minimum temperature and maximum temperature of, respectively, between 0.03 and 0.47, and 0.32–0.45 °C for this time period. The results of the groundwater modelling suggest that water levels on the Kerdi-Shirazi plain will continue to decline over the forecast period with decreases of 34.51, 36.57 and 33.58 m being predicted, respectively, for climate scenarios A1B, A2 and B1. Consequently, groundwater resources in the Kerdi-Shirazi plain will urgently need active management to minimize the effects of ongoing water level decline and to prevent saltwater intrusion and desertification in the region.     

Land use change modelling: current practice and research priorities

Land use change models are tools to support the analysis of the causes and consequences of land use dynamics. Scenario analysis with land use models can support land use planning and policy. Numerous land use models are available, developed from different disciplinary backgrounds. This paper reviews current models to identify priority issues for future land use change modelling research. This discussion is based on six concepts important to land use modelling: (1) Level of analysis; (2) Cross-scale dynamics; (3) Driving forces; (4) Spatial interaction and neighbourhood effects; (5) Temporal dynamics; and (6) Level of integration. For each of these concepts an overview is given of the variety of methods used to implement these concepts in operational models. It is concluded that a lot of progress has been made in building land use change models. However, in order to incorporate more aspects important to land use modelling it is needed to develop a new generation of land use models that better address the multi-scale characteristics of the land use system, implement new techniques to quantify neighbourhood effects, explicitly deal with temporal dynamics and achieve a higher level of integration between disciplinary approaches and between models studying urban and rural land use changes. If these requirements are fulfilled models will better support the analysis of land use dynamics and land use policy formulation.     

Investigating effects of land use change scenarios on soil erosion using CLUE-s and RUSLE models

Predicting soil erosion change is an important strategy in watershed management. The objective of this research was to evaluate land use change effects on soil erosion in the north of Iran using five land use scenarios. Three land use maps were created for a period of 25 years (1986–2010) to investigate land use transition and to simulate land use for the year 2030. Additionally, the RUSLE model was used to estimate erosion and the effect of land use change. The results showed that CLUE-s is suitable for modeling future land use transition using ROC curve. The median soil loss in the basis period was 104.52 t ha^?1 years^?1. Results indicate that the range of soil loss change is 2–32% in simulated period and soil loss value was higher than basis period in all scenarios. Thirty percent decrease in demand scenario has the lowest soil loss in simulated period, and the soil loss value under this scenario will be only 2% more than the basis period. Thus, the soil conversion effects resulted from the demand of each land use.     

Present groundwater status in Egypt and the environmental impacts

This article is an attempt to give a brief review on the status of groundwater studies in Egypt, their results, and the present plans for groundwater development that are usually based on the hydrogeological characteristics of the groundwater resources as well as on the environmental control of the discharge area.In terms of groundwater hydrology, Egypt can be divided into the following groundwater provinces: (1) the Western Desert, (2) the Eastern Desert, (3) the Nile Valley including the delta, (4) the Sinai Peninsula, (5) the Northern Coastal Zone, and (6) Wadi El-Natrun.The studies of volume and nature of groundwater and the environmental impact studies that were carried out in each of these provinces differed according to the importance given to development of projects in areas of interest and to the availability of funds. Recent studies and the surveys conducted for groundwater hydrological research by local and international organizations are described separately for each province. Special reference is made to groundwater hydro-geological setting, groundwater resources evaluation, and present and future utilization. The New Valley is the largest Egyptian irrigated agricultural development project that is solely dependent on groundwater resources. An outline showing its nature, objective, and size is included as an example of groundwater development.     

Impacts of land use change and groundwater management on long-term nitrate-nitrogen and chloride trends in groundwater of Jeju Island,Korea

Impacts of land use changes and groundwater management actions on groundwater quality were evaluated at the island scale with spatiotemporal trends of NO₃-N and Cl concentrations in groundwater of Jeju Island, Korea. The temporal trends from 1993 to 2012 in the concentrations of NO₃-N and Cl from more than 3900 wells were estimated using the Mann–Kendall trend test and Sen’s slope analysis and compared with the land use change trend for the period 1995–2009. The results indicate that the upward trends in NO₃-N were associated with the expansion of agricultural lands, whereas Cl trends were considered to be affected by other factors in addition to the land use changes. In the mid-mountainous region, the deterioration in the groundwater quality by the both NO₃-N and Cl was expected due to the continuous expansion of agricultural lands. In the lowland area, the NO₃-N and Cl components showed different trends depending on the regions. In the eastern area, increasing trends in NO₃-N were observed due to the development of new agricultural areas, while the Cl concentration was observed to decrease as a result of the regulation on groundwater extraction to reduce seawater intrusion. Our study highlights that a comprehensive interpretation of trends in NO₃-N and Cl and land use changes for long-term periods can provide useful insights to prepare for suitable groundwater management plans in the whole island perspective.     

A flood vulnerability index for coastal cities and its use in assessing climate change impacts

Worldwide, there is a need to enhance our understanding of vulnerability and to develop methodologies and tools to assess vulnerability. One of the most important goals of assessing coastal flood vulnerability, in particular, is to create a readily understandable link between the theoretical concepts of flood vulnerability and the day-to-day decision-making process and to encapsulate this link in an easily accessible tool. This article focuses on developing a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding. It is applied to nine cities around the world, each with different kinds of exposure. With the aid of this index, it is demonstrated which cities are most vulnerable to coastal flooding with regard to the system??s components, that is, hydro-geological, socio-economic and politico-administrative. The index gives a number from 0 to 1, indicating comparatively low or high coastal flood vulnerability, which shows which cities are most in need of further, more detailed investigation for decision-makers. Once its use to compare the vulnerability of a range of cities under current conditions has been demonstrated, it is used to study the impact of climate change on the vulnerability of these cities over a longer timescale. The results show that CCFVI provides a means of obtaining a broad overview of flood vulnerability and the effect of possible adaptation options. This, in turn, will allow for the direction of resources to more in-depth investigation of the most promising strategies.