基于模糊综台评价法的区域水资源承载力研究

区域水资源承载力是进行生态环境建设和确定社会经济发展的基础.分析了水资源承载力的内涵及其评价方法,选取人均供水量、水资源利用率、单位GDP用水量、供水模数、需水模数、生态用水率等6个主要因素作为评价指标,建立了水资源承载力模糊综合评判模型,并应用该模型对榆林市水资源进行综合评价.结果表明:榆林市水资源开发利用已经达到相当规模,在现有经济技术条件下,该地区的水资源承载潜力已相对较小,水资源供需矛盾突出.同时,提出了提高水资源承载力的对策,为今后的区域水资源开发利用提供依据.     

宿迁市黄河故道及以南地区水资源优化配置研究

研究宿迁市黄河故道及以南地区水资源优化配置。基于对宿迁市黄河故道及以南地区的分析和概化,建立了宿迁市黄河故道及以南地区水资源优化配置数学模型,并运用改进型量子遗传算法对该地区不同保证率工况进行了分析计算。结果表明,该研究区域水资源经优化配置后,总缺水量和总弃水量明显减少,水资源利用率得到了显著提高。该方法易于操作,所得结果合理,具有较好的实用价值。     

辽宁西北区水资源短缺问题分析及解决途径

本文从区域水量平衡出发,分析了辽西北半干旱地区水资源短缺的主要原因,对水资源未来变化趋势进行了宏观估测,通过辽西北水资源总体规划和开发利用实践,进而提出了解决或缓解该类型区水资源短缺的基本途经和措施.     

格尔木河流域的地下水合理开发利用模式研究

针对青海省格尔木河流域水资源开发利用需求量,分析其对下游盐湖生态需水量产生的影响.根据流域概况,建立格尔木河流域水资源数学模拟模型,利用数学模拟模型进行预测,探讨格尔木河流域的水资源合理开发利用模式并提合理的建议.     

甘肃省水资源区域优势综合评价与分析

水资源的过多或过少都会导致危机。优化配置水资源，是推动西部地区经济社会可持续发展的关键。如何实现水资源的优化配置，是政府主管部门、众多学者共同关心的问题。通过对甘肃省水资源区域优势的综合评价．揭示甘肃不同地区水资源的丰亏状况，为寻求经济发展与生态建设、水资源合理开发利用的最佳结合点提供科学依据。     

云南滇中高原调水工程建设的必要

滇中地区是云南省经济最为活跃的地区，由于特殊的自然地理条件，资源性和水质性缺水导致该地区目前供水紧张，加剧了该区供水矛盾，水问题已逐渐成为该区经济社会和谐发展的瓶颈因素。从滇中地区水资源状况开发利用程度，滇中地区缺水对社会经济造成的影响等方面，分析了滇中高原调水工程建设的必要性和紧迫性。     

辽宁西北区水资源短缺问题分析及解决途径

本文从区域水量平衡出发,分析了辽西北半干旱地区水资源短缺的主要原因,对水资源未来变化趋势进行了宏观估测,通过辽西北水资源总体规划和开发利用实践,进而提出了解决或缓解该类型区水资源短缺的基本途经和措施。     

基于灰色关联分析的鄂尔多斯市水资源承载力评价

水资源承栽力是进行区域生态环境建设和确定社会经济发展方向的基础.以鄂尔多斯市水资源承栽力为研究对象,选取了水资源开发利用率、耕地灌溉率、地表水控制率、工业用水重复利用率、人均水资源可利用量、人均供水量、排污率、供水模数和生态用水率9个主要因素作为评价因素,应用灰色关联度分析法对鄂尔多斯市及各分区水资源承栽力进行了评价.结果表明:目前水资源开发利用已经达到相当规模,在现有经济技术条件下,该地区的水资源承栽潜力已相对较小,水资源供需矛盾突出.从社会、经济的进一步发展和保护生态环境出发,通过调整产业结构、节水工程建设、增加非常规水利用量、水权转换工程和节水型社会制度建设等措施提高水资源承载能力,合理利用本地水资源.     

云南滇中高原调水工程建设的必要性和紧迫性

滇中地区是云南省经济最为活跃的地区，由于特殊的自然地理条件，资源性和水质性缺水导致该地区目前供用水紧张，加剧了该区供用水矛盾，水问题已逐渐成为该区经济社会和谐发展的瓶颈因素。从滇中地区水资源状况及开发利用程度，滇中地区缺水对社会经济造成的影响等方面。分析了滇中高原调水工程建设的必要性和紧迫性。     

阜新市灌溉节水分区及节水途径

1 分区的原则与方法灌溉节水分区与自然条件、经济条件、水资源条件、灌溉节水措施等诸多因素有关,其基本原则有三条: a.发展灌溉节水措施的区域,其自然条件(气候、地形等)和水资源的开发利用条件基本相同或相似。 b.尽可能保持县、乡级的行政区界和已     

Sprinkler water distributions as affected by winter wheat canopy

Sprinkler uniformity is often used to evaluate irrigation system performance. The measurement of uniformity is generally made from one test when no crop is present. However, a developing crop canopy has significant potential to modify the distribution of water applied during irrigation. This study was conducted to evaluate the influence of a winter wheat canopy on sprinkler uniformity and on canopy-intercepted water by measuring water distributions above and below the canopy. The Christiansen uniformity coefficient (CU) was calculated on both a daily and a cumulative basis. The CU was higher below the canopy than above the canopy. Canopy-intercepted water, which is here defined as the sum of canopy storage and stemflow, increased with increasing water application depth. Sprinkler uniformity had no significant effect on the mean amount of water interception by the canopy. The ratio of water interception to total water application depth for the whole irrigation season was between 0.24 and 0.28. The CUs calculated from the cumulative depth caught above and below the canopy are larger than the averages of individual CU values during the irrigation season. Measurement of individual CUs during the irrigation season therefore underestimates the cumulative CU. Experimental results also demonstrated that sprinkler uniformity in this study had little effect on crop yield. Received: 1 February 2000     

基于水土保持措施因子及其分布特征探析

通过对水土保持的生物措施因子、工程措施因子及耕作措施因子初步分析,提出了水土保持所应采取的措施,为今后水土保持提供可以借鉴的参考依据.     

Improving water use efficiency as part of integrated catchment management

Sustainable agricultural development requires technologies and practices that make more efficient and productive use of resources and an enabling environment that encourages the adoption of these technologies. Many institutions and international agencies are showing considerable interest in integrated catchment management (ICM) as a practical means of improving the management of water resources, reducing environmental degradation and promoting sustainable agricultural development. This paper outlines some of the main components of ICM and lists some of the prerequisites for establishing collective responsibility for, in particular, groundwater resources. This paper also discusses the extent to which programmes of ICM can be used as a means of conserving water resources and improving water use efficiency and productivity at the farm and catchment scales.     

Simulation of yield decline as a result of water stress with a robust soil water balance model

The relative yield decline that is expected under specific levels of water stress at different moments in the growing period is estimated by integrating the FAO K_y approach [Doorenbos, J., Kassam, A.H., 1979. Yield response to water. FAO Irrigation and Drainage Paper No. 33. Rome, Italy] in the soil water balance model BUDGET. The water stored in the root zone is determined in the soil water balance model on a daily basis by keeping track of incoming and outgoing water fluxes at its boundary. Given the simulated soil water content in the root zone, the corresponding crop water stress is determined. Subsequently, the yield decline is estimated with the K_y approach. In the K_y approach the relation between water stress in a particular growth stage and the corresponding expected yield is described by a linear function. To account for the effect of water stresses in the various growth stages, the multiplicative, seasonal and minimal approach are integrated in the model. To evaluate the model, the simulated yields for two crops under various levels of water stress in two different environments were compared with observed yields: winter wheat under three different water application levels in the North of Tunisia, and maize in three different farmers’ fields in different years in the South West of Burkina Faso. Simulated crop yields agreed well with observed yields for both locations using the multiplicative approach. The correlation value (R²) between observed and simulated yields ranged from 0.87 to 0.94 with very high modeling efficiencies. The root mean square error values are relatively small and ranged between 7 and 9%. The minimal and seasonal approaches performed significantly less accurately in both of the study areas. Estimation of yields on basis of relative transpiration performed significantly better than estimations on basis of relative evapotranspiration in Burkina Faso. A sensitivity analysis showed that the model is robust and that good estimates can be obtained in both regions even by using indicative values for the required crop and soil parameters. The minimal input requirement, the robustness of the model and its ability to describe the effect on seasonal yield of water stress occurring at particular moments in the growing period, make the model very useful for the design of deficit irrigation strategies. BUDGET is public domain software and hence freely available. An installation disk and manual can be downloaded from the web.     

Canopy temperature variability as an indicator of crop water stress severity

Irrigation scheduling requires an operational means to quantify plant water stress. Remote sensing may offer quick measurements with regional coverage that cannot be achieved by current ground-based sampling techniques. This study explored the relation between variability in fine-resolution measurements of canopy temperature and crop water stress in cotton fields in Central Arizona, USA. By using both measurements and simulation models, this analysis compared the standard deviation of the canopy temperature to the more complex and data intensive crop water stress index (CWSI). For low water stress, field was used to quantify water deficit with some confidence. For moderately stressed crops, the was very sensitive to variations in plant water stress and had a linear relation with field-scale CWSI. For highly stressed crops, the estimation of water stress from is not recommended. For all applications of one must account for variations in irrigation uniformity, field root zone water holding capacity, meteorological conditions and spatial resolution of T _c data. These sensitivities limit the operational application of for irrigation scheduling. On the other hand, was most sensitive to water stress in the range in which most irrigation decisions are made, thus, with some consideration of daily meteorological conditions, could provide a relative measure of temporal variations in root zone water availability. For large irrigation districts, this may be an economical option for minimizing water use and maximizing crop yield.

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Effect of soil texture and CaCO3 content on water infiltration in crusted soil as related to water salinity

Summary The effect of soil texture and CaCO₃ content on water infiltration rate in crusted soil was studied with the use of a rain simulator. Two types of soils with low exchangeable sodium percentage (ESP < 3.0%) were studied: (i) calcareous soils (5.1–16.3% CaCO₃) with a high silt-to-clay ratio (0.82–1.47) from a region with < 400 mm winter rain; and (ii) non-calcareous soils with a low silt-to-clay ratio (0.13–0.35) from a region with > 400 mm winter rain. Soil samples with clay percentages between 3 and 60 were collected in each region. Distilled water (simulating rainfall) and saline water (simulating irrigation water) were sprinkled on the soil. The soils were exposed to rain until steady state infiltration and corresponding crust formation were obtained. For both types of soils and for both types of applied water, soils with 20% clay were found to be the most sensitive to crust formation and have the lowest infiltration rate. With increasing percentage of clay, the soil structure was more stable and the formation of crust was diminished. In soils with lower clay content (< 20%), there was a limited amount of clay to disperse and, as a result, undeveloped crust was formed. Silt and CaCO₃ had no effect on the final infiltration rate for either type of applied water, whereas with saline water, increasing the silt content increased the rate of crust formation.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1130-E, 1984 series     

A model for computing date palm water requirements as affected by salinity

Irrigation of crops in arid regions with marginal water is expanding. Due to economic and environmental issues arising from use of low-quality water, irrigation should follow the actual crop water demands. However, direct measurements of transpiration are scant, and indirect methods are commonly applied; e.g., the Penman–Monteith (PM) equation that integrates physiological and meteorological parameters. In this study, the effects of environmental conditions on canopy resistance and water loss were experimentally characterized, and a model to calculate palm tree evapotranspiration ET_c was developed. A novel addition was to integrate water salinity into the model, thus accounting for irrigation water quality as an additional factor. Palm tree ET_c was affected by irrigation water salinity, and maximum values were reduced by 25 % in plants irrigated with 4 dS m^?1 and by 50 % in the trees irrigated with 8 dS m^?1. Results relating the responses of stomata to the environment exhibited an exponential relation between increased light intensities and stomatal conductance, a surprising positive response of stomata to high vapor pressure deficits and a decrease in conductance as water salinity increased. These findings were integrated into a modified ‘Jarvis–PM’ canopy conductance model using only meteorological and water quality inputs. The new approach produced weekly irrigation recommendations based on field water salinity (2.8 dS m^?1) and climatic forecasts that led to a 20 % decrease in irrigation water use when compared with current irrigation recommendations.     

Evapotranspiration of citrus as affected by soil water deficit and soil salinity

Summary The extent to which evapotranspiration (ET) of Valencia citrus trees is affected by differing soil water depletions (SWD) and soil salinity regimes was determined during five seasons during which soil salinity levels varied. Three weighing lysimeters, each with a 14 year old tree, were used to measure daily ET and to schedule irrigation to maintain SWD at maxima of 15, 75 and 150 mm respectively. Tensiometers and salinity sensors were used to indicate the in situ soil matric and soil solution osmotic potentials. Total soil water potential was calculated from tensiometer and salinity sensor readings weighted for root density with depth. The total of these for the summer months was found to be linearly related (Fig. 5) to the mean ET/Ep (Ep=A-pan evaporation). The slope and threshold of ET reductions with decreasing soil water potential for the low frequency irrigation treatment (150 mm SWD) show good agreement with the slope and threshold of yield decrease that is calculated from soil salinity in the lysimeter using previously reported salinity-yield relationships. The reduced water uptake due to increasing soil salinity has important implications for soil salinity control, since the lower uptake should in theory increase the leaching fraction. This implies a degree of self adjustment to the leaching fraction when irrigating with increasingly saline waters if water applications are scheduled as for non-saline conditions.     

Economic factors and opportunities as determinants of water use efficiency in agriculture

A consequence of water scarcity is that it has enhanced research and development aimed at increasing water use efficiency in irrigated agriculture. Although biological, genetic, and technological achievements may induce potential high levels of water use efficiency, actual observed values may be much smaller. This paper distinguishes between potential and actual water use efficiency measures, and discusses factors and opportunities that may affect actual water use efficiency in irrigated agriculture. These include economic forces, environmental effects, and institutional arrangements, each of which may affect water use decisions at field, farm, regional, and national levels. The paper develops a scheme to generally address differences between private and social considerations that determine water use efficiency decisions. Using this scheme, several examples from California and Israel are provided to support the arguments. The paper concludes that the concept of water use efficiency is much broader than its definition: yield per water applied or transpired. Moreover, determination of water use efficiency levels in irrigated agriculture is a complex issue that requires interdisciplinary considerations.     

Assessment of emitter discharge in microirrigation system as affected by polluted water

A drip irrigation system has the advantage of maintaining high water content near the plant root. However, its performance depends on water quality as it may induce the emitter clogging. In the Tohaku National Irrigation Project, in western Japan, mist spray emitters are widely used for irrigation in the field and greenhouses for vegetable and orchard crops. Seven emitters of different types were evaluated for the variation in their discharge rate without filter. The statistical analysis of mean discharge ratio and the coefficient of variation of the performance of emitters along a lateral line in the field indicated that the mist spray emitters had the best performance for irrigation in Tohaku area, particularly the new emitters or 1-year old emitters. The results suggest that after using the emitter line for two irrigation seasons it should either be replaced in the third season or washed carefully if further used.