WATER EXCHANGES: TOOLS TO BEAT EL NIÑO CLIMATE VARIABILITY IN IRRIGATED AGRICULTURE1

ABSTRACT: Using a case study of the Yakima River Valley in Washington State, this paper shows that relatively simple tools can be used to forecast the impact of the El Niño phenomenon on water supplies to irrigated agriculture, that this information could be used to estimate the significantly shifted probability distribution of water shortages in irrigated agriculture during El Niño episodes, and that these shifted probabilities can be used to estimate the value of exchanges of water between crops to relieve some of the adverse consequences of such shortages under western water law. Further, recently devised water‐trading tools, while not completely free under western water law to respond to forecasted El Niño episodes (ocean circulation patterns), are currently being employed during declared drought to reduce the devastating effects of water shortages in junior water districts on high valued perennial crops. Additional institutional flexibility is needed to take full advantage of climate forecasting, but even current tools clearly could prove useful in controlling the effects of climate variability in irrigated agriculture. Analysis shows the significant benefit of temporarily transferring or renting water rights from low‐value to high‐value crops, based on El Niño forecasts.     

SEDIMENT TRAPPING WITHIN FORESTRY STREAMSIDE MANAGEMENT ZONES: GEORGIA PIEDMONT,USA1

ABSTRACT: The effectiveness of streamside management zones (SMZs) was assessed for reducing sediment transport from concentrated overland flow draining two Georgia Piedmont clearcuts that had undergone mechanical and chemical site preparation and planting. Silt fences were used to trap sediment transport from zero‐order ephemeral swales at the edge of and within SMZs. Four control swales and nine treatment swales were studied. A double mass curve approach was used to graphically compare sediment accumulation rates at the edge of SMZs to accumulation rates within the SMZs at a distance consistent with current recommendations for SMZ width in Georgia. SMZ efficiencies for trapping sediment transported by concentrated flow ranged from 71 to 99 percent. No statistical model was found to explain how SMZ efficiencies varied with SMZ and contributing area characteristics. Measured sediment accumulations at the SMZ boundary were compared to Revised Universal Soil Loss Equation (RUSLE) predictions of up‐ slope erosion, and a delivery ratio of 0.25 was calculated. SMZs had a quantifiable and substantial ameliorating effect on sediment transport from concentrated overland flow on the clearcut study sites.     

STREAMFLOW CHARACTERISTICS OF SMALL WATERSHEDS IN THE BLUE MOUNTAINS OF OREGON1

ABSTRACT: Streamflow data for water years 1978–84 were evaluated to identify streamflow characteristics for 13 small watersheds (0.46–7.00 mi²) in the Blue Mountains of eastern Oregon and to determine differences among grazing intensities and vegetation types. The ranges for mean annual water yields, peak flows, and 7-day low flows for the 13 watersheds were 5.5–28.1 inches, 2.0–34.7 cfsm, and 0.006–0.165 cfsm, respectively. Two classes of vegetation were evaluated: (1) western larch-Douglas-fir (nine watersheds) and (2) other (four watersheds representing fir-spruce, lodgepole pine, ponderosa pine, and mountain meadow). The means for annual peak flows and the slopes of the flow.duration curve were significantly different (p=0.05) for the two vegetation classes; differences in mean annual water yield were marginallysignificant(0.05< p <0.10). After they were adjusted for precipitation, the means for annual water yield, peak flows, and slopes of the flow-duration curve were significantly different for the two vegetation classes; differences in the means for annual 7-day low flows were marginally significant. The western larch-Douglas-fir group had somewhat lower water yields but, overall, tended to have more favorable streamfiow characteristics including lower peak flows, higher low flows, and more evenly distributed flow regimes (flatter flow-duration curves) than the “other” class. Four levels of grazing intensity had no effect on streamilow characteristics.     

A STOCHASTIC MODEL TO EVALUATE RIPARIAN IRRIGATION EXPANSION IN THE EASTERN UNITED STATES1

ABSTRACT: Irrigation has expanded in parts of the eastern United States. In some areas, the adjoining surface (riparian) water is the most economical source of irrigation water. Expanded demand for riparian water may lead to conflict among irrigators and other streamflow users. Accurate information on the potential for and impacts of riparian irrigation expansion is needed to decide if control of such expansion is necessary. In this study, a stochastic economic model to evaluate the impacts of potential irrigation expansion is presented. The model considers the soil, location, and land use characteristics of individual sites, as well as weather and streamflow patterns. The application of the model to an eastern Virginia watershed indicates that, with maximum potential expansion, water availability becomes limited and yields will be reduced in some years. As a result, the expected net returns from irrigation and the probability of breaking even on the investment are reduced substantially. The results suggest the need to consider regulation of surface water allocation for irrigation development in riparian watersheds.     

INTERSTATE WATER ALLOCATION COMPACTS IN THE WESTERN UNITED STATES - SOME SUGGESTIONS1

ABSTRACT: Agreements between states, or compacts, provide a mechanism for resolving transboundary resource issues. The twenty-two compacts allocating the water of rivers among states in the western United States are examined to provide guidance for drafters of future compacts. The method of allocation selected for a compact reflects the state's allocation of the risk of dry years. Allocations based on models have been unsuccessful. Percentage allocations are good for fairly apportioning risk, but conflict with principles of prior appropriation. Guarantees of minimum flows should be used with great care, to avoid any state becoming a guarantor of natural phenomena over which it has no control. Disputes should be anticipated, and a dispute resolution mechanism agreed upon. Arbitration or litigation are likely to prove the most politically acceptable. Compacts should be comprehensive in scope, encompassing groundwater as well as surface use. Federal claims should also be addressed, and some form of protection from subsequent changes of federal policy should be incorporated in the agreement and its ratifying legislation.     

维护生态环境 促进经济发展

本文阐述了生态环境与社会经济之间的关系，探讨了保护环境、资源对发展经济的作用。     

TECHNICAL CLARITY IN INTER-AGENCY NEGOTIATIONS: LESSONS FROM FOUR HYDROPOWER PROJECTS1

ABSTRACT: We investigated the effect of technical clarity on success in multi-party negotiations in the Federal Energy Regulatory Commission (FERC) licensing process. Technical clarity is the shared understanding of dimensions such as the geographic extent of the project, range of flows to be considered, important species and life stages, and variety of water uses considered. The results of four hydropower licensing consultations are reported. Key participants were interviewed to ascertain the level of technical clarity present during the consultations and the degree to which the consultations were successful. Technical clarity appears to be a prerequisite for successful outcomes. Factors that enhance technical clarity include simple project design, new rather than existing projects, precise definition of issues, a sense of urgency to reach agreement, a sense of fairness among participants, and consistency in participation. Negotiators should not neglect the critical pre-negotiation steps of defining technical issues and determining appropriate studies, deciding how to interpret studies, and agreeing on responses to study results.     

STATUS OF RIPARIAN ECOSYSTEMS IN THE UNITED STATES1

ABSTRACT: An attempt was made to review all available data on the extent and status of riparian ecosystems in the U.S.A. This report presents a synthesis of the findings, including some estimates of how much land was originally covered by woody riparian vegetation, and how much remains in that condition today. A synopsis of information is presented on the status of riparian ecosystems in each of 10 regions: California, Pacific Northwest, Rocky Mountain, Arid Southwest, Plains-Grasslands, Lake States, Corn Belt, Mississippi Delta, Northeast-Appalachian, and Southeast. Woody riparian plant communities once covered an estimated 75 to 100 million acres of land in the contiguous 48 states. Mankind has converted at least two-thirds of that nationwide acreage to other non-forest land uses and it is estimated that only 25 to 35 million acres of riparian plant communities remain in a near natural condition. Across the country, loss of riparian acreages is directly attributable to water resource development (especially channel modification and water impoundment), floodplain clearing for agriculture, and urbanization. In many states of the arid west, the midwest, and the lower Mississippi alluvial valley, riparian vegetation has been reduced in area by more than 80 percent. Riparian woodlands are one of this country's most heavily modified natural vegetation types.     

洗车废水的污染与环境管理研究

本文分析了洗车所造成的水资源的浪费、对环境的污染以及对道赂交通、居民、行人的影响，介绍了我国对洗车废水管理的现状，并从法制建设、执法监督、废水处理，先进洗车技术推广、宣传教育等方面提出了针对我国洗车废水污染的环境管理对策建议。     

美国职业卫生法规、监管及统计体系

美国是工业发达国家,是世界上最早建立“职业安全和卫生法”的国家之一。基于该法,美国确立以职业安全卫生监察局(OSHA)为执法机构、职业安全卫生复审委员会(OSHRC)为监督机构的职业卫生监管体系;同时,以劳工统计局(BLS)为统计主管机构,建立以“1904规范”为基础的企业雇主对其作业场所职业卫生记录和报告制度,并辅以两种形式的政府主动调查,形成了自下至上和自上至下相结合的调查统计体系。目前,我国职业卫生的调查统计体系尚未形成。因此,需要从工业发达国家的职业卫生法规、监管入手,以系统的方法和思路,分析其调查统计体系,学习工业发达国家的经验。研究结果认为美国的职业卫生统计体系具有上层法律及相关条例完备、组织体系职责分明、形成了政府主动调查与企业记录报告相结合的调查统计体系等明显的特点。