REGIONAL ASSESSMENT OF NLEAP NO3-N LEACHING INDICES1

ABSTRACT: Nonpoint source ground water contamination by nitrate nitrogen (NO₃-N) leached from agricultural lands can be substantial and increase health risks to humans and animals. Accurate and rapid methods are needed to identify and map localities that have a high potential for contamination of shallow aquifers with NO₃-N leached from agriculture. Evaluation of Nitrate Leaching and Economic Analysis Package (NLEAP) indices and input variables across an irrigated agricultural area on an alluvial aquifer in Colorado indicated that all leaching indices tested were more strongly correlated with aquifer NO₃-N concentration than with aquifer N mass. Of the indices and variables tested, the NO₃-N Leached (NL) index was the NLEAP index most strongly associated with groundwater NO₃-N concentration (r² values from 0.37 to 0.39). NO₃-N concentration of the leachate was less well correlated with ground water NO₃-N concentration (r² values from 0.21 to 0.22). Stepwise regression analysis indicated that, although inorganic and organic/inorganic fertilizer scenarios had similar r² values, the Feedlot Indicator (proximity) variable was significant over and above the NO₃-N Leached index for the inorganic scenario. The analysis also showed that combination of either Movement Risk Index (MIRI) or NO₃-N concentration of the leachate with the NO₃-N Leached index leads to an improved regression, which provides insight into area-wide associations between agricultural activities and ground water NO₃-N concentration.     

A NEW APPROACH FOR ESTIMATING IRRIGATION CONVEYANCE LOSSES AND THEIR ECONOMIC EVALUATION1

ABSTRACT: In this paper a new methodology for estimating conveyance efficiency within irrigation systems is presented. Based on statistical analysis of daily water releases from the source of supply and deliveries to the farmers in an irrigation district in Mexico, a linear model is obtained for estimating conveyance efficiency and two component factors. One of these factors points out the relative importance of the operational losses (i.e., losses due to water management), and the second shows the importance of the fixed losses which can be attributed to the average flow through the canal network without variations. In the last part of this paper, an analysis of the expected benefits and costs accruing from system improvement permits derivation of a decision rule which may be used for analyzing the economic feasibility of lining in-place canals.     

Multi-Criteria Decision Analysis of Treated Wastewater Use for Agriculture in Water Deficit Regions1

Al-Juaidi, Ahmed E., Jagath J. Kaluarachchi, and Ungtae Kim, 2010. Multi-Criteria Decision Analysis of Treated Wastewater Use for Agriculture in Water Deficit Regions. Journal of the American Water Resources Association (JAWRA) 46(2):395-411. DOI: 10.1111/j.1752-1688.2009.00409.x Abstract: Coastal regions such as the Gaza Strip of Palestine with limited freshwater supply suffer significantly due to the rapid depletion of water levels, seawater intrusion, and increased water demands. In such regions, use of treated wastewater (TWW) is a viable option if public health issues are addressed. The goal of this paper is to address the use of TWW in agriculture while considering net benefit, economic efficiency of water use (EEWU), environmental goals, and public health risks. The proposed methodology considers public health risk assessment and multi-criteria decision analysis to assess the beneficial use of TWW in agriculture. The methodology was demonstrated for the Gaza Strip. The health risk assessment suggests that increasing the elapsed time between irrigation and consumption and switching from surface to sprinkler and drip irrigation are practical measures to reduce public health risks. The optimization and decision analyses show that proper allocation of freshwater and TWW and distribution of land area by crop type can significantly increase the net benefit and EEWU. In most cases, net benefit increased by 44%, groundwater use reduced 29% while increasing the EEWU by threefold compared with the existing conditions. The multi-criteria decision analysis with weighted goal programming can develop flexible management options that considers a given decision-maker preference. When groundwater abstraction for agriculture reduced from 57 to 36 Mm³ as per decision analysis, the corresponding area below mean sea level decreased by 58% indicating significant aquifer recovery.     

FACTUAL INPUTS FOR ALLOCATION DECISIONS CONCERNING SCARCE WATER RESOURCES1

ABSTRACT: Factual inputs which may be useful for completing first-order assessments to aid decision-making on the allocation of scarce water resources are compiled. Water needs of major manufacturing industry groups and of minerals industries show wide variations in several measures of water use intensity. The chemicals and allied products and primary metals industries dominate the total water intake and consumptive water use by manufacturing industries. Consumptive use per employee for the petroleum and coal products industry group is nearly 2.5 times higher than that for any other industry group. Estimates of the water requirements per unit energy output for energy-processing systems vary by as much as an order of magnitude. Agricultural water use is larger than that of any other industry but water use for irrigation is not expected to increase significantly by the year 2020. In California, the production of crop calories and proteins per unit of irrigation water applied may vary by more than an order of magnitude. Crops which offer larger monetary returns per acre are irrigated most frequently.     

污水灌溉对地下水污染的机理研究

以焦作市南部新河沿岸灌溉区为研究对象,分别用污水和大气降水进行了土柱淋滤模拟实验,分析了氯离子、总硬度及TDS在土壤中的迁移转化机理.实验结果表明,渗出液中的污染物浓度最初较小,随后出现最大值,最后开始下降.表明当地浅层地下水中氯离子、总硬度及TDS污染与污水灌溉有关.     

A TRADE-OFF ANALYSIS OF ALTERNATIVE WATER USES1

ABSTRACT: In the western United States, hydropower and agriculture often cempete for surface waters. Since water markets are imperfect, allocations are often made through institutional arrangements and policy The purpose of this paper is to compare the gross water returns from agriculture with hydropower in terms of water use in Idaho. For the year 1986, returns from agriculture averaged $200 per acre-foot, and returns from hydropower averaged $8.00 per acre-foot.     

崇明岛地下水资源的利用现状及保护措施

未来地下水资源短缺,特别是由于地面沉降、地表退化、海平面上升等引起的地下水位下降,将对沿海地区的地质环境及人类的生存发展产生极大的影响。通过对崇明地区地下水资源利用现状以及影响地下水位下降的影响因素分析,提出了改善传统的灌溉系统来减少地下水资源的使用、海岸沿线修建人工湖泊防止海水入侵、鼓励农民大面积种植水稻、制定管理措施严格控制地下水的开采总量、进一步加强崇明岛地面沉降动态监测与研究等相应的防范措施。强调控制地下水位的下降,以减轻淡水资源短缺所造成的危害,具有特殊而重要的意义。     

南方海涂海水灌溉库拉索芦荟的试验研究

在海南海涂沙滩(非耕地资源)对药用植物库拉索芦荟进行海水灌溉试验,设6种处理,淡、海水配比分别为A1(CK):100∶0;A2:90∶10;A3:75∶25;A4:50∶50;A5:25∶75;A6:0∶100。结果表明:①用一定浓度范围的海水灌溉时,库拉索芦荟苗期返青系数、根的综合生长量等植物生态指标为处理A3>A2>A1,超过一定海水浓度后则递减;连续3年的田间试验表明,芦荟叶片鲜重、干重A1、A2、A3三种处理间没有显著差异,而根干重A3显著高于A1,A4比A1处理叶片鲜重、干重减产均在20%以内,表明海水灌溉库拉索芦荟是可行的。②海水灌溉明显推迟芦荟从营养生长向生殖生长的转化时期,随着海水比例的增加,抽苔期明显推迟。③各种处理海水灌溉的沙滩深度在0～10cm范围内,盐分含量随深度迅速下降,10cm以下下降幅度变缓;经3年的海水灌溉试验,海涂沙滩在未作任何人为调控措施下,0～50cm沙滩含盐量仍在0.3%范围内。