System Water Balance Research Articles

Characteristics of water reuse and its effects on paddy irrigation system water balance and the riceland ecosystem

Rapid industrial development in the rice-growing regions has increased competition for the scarce water resources. Water reuse (surface and subsurface agriculture drainage water, storm runoff, sewerage effluent and industrial wastewater recycling) is in widespread use as a method of supplementing the paddy water supply, therefore, there is a need to clarify its effects on the paddy system water balance and riceland ecosystem. Field data and simulation results from a complex runoff model (created on a daily basis), were used to estimate the water balance and assess the effects on the irrigation system of a water shortage area in Niigata Prefecture, Japan. For three years (1991–1993), the average water reuse component was within the range 14∼ 15% of the total irrigation water supply. Apart from meeting the water needs at peak demand periods, water reuse is a quick-response water supply solution during dry spells, increasing both the water reliability and crop security. To understand the impact of water reuse on the riceland ecosystem, its effect on total phosphorus (T-P), total nitrogen (T-N), suspended solids (SS), and chemical oxygen demand (COD) was assessed. Blending of the drainage water was done to reduce the irrigation water concentrations, to approximate the traditional dual canal system and to increase farmer satisfaction with the water reuse system. Apart from the fact that the amount of return flow drained out of the irrigation system was reduced when drainage water was reused for irrigation, the effluent load reductions for SS and T-P owing to water reuse were consistently high. Hence, water reuse not only helps meet irrigation water needs, but also aids purification of the agricultural drainage water and preservation of the riceland ecosystem.

Assessing options for stream regulation using hydrologic simulations and cumulative impact analysis: Flathead River Basin, U.S.A.

AbstractThis study attempted to resolve regulation problems up‐ and downstream of Flathead Lake and on the lake proper. Members of a technical working group, representing eight water and wildlife management agencies, contributed 75 regulation scenarios they deemed necessary to conserve or enhance ecological (fish and wildlife) and societal (hydropower production, flood control, and recreation) resources for which they had management authority. The hydrology model simulated the effect of each scenario on system water balance; scenarios that were within the physical and legal constraints of the system were accepted for determination of cumulative impacts on resources. A multiattribute tradeoff analysis was used to assess cumulative impacts to key resources as a consequence of each regulation scenario (simulation) accepted for evaluation. Impacts were subjectively and independently quantified by each member of the working group following a point and importance weighting system agreed to a priori. Valuation of impacts was done on the basis of 36 technical studies of the effects of regulation on system resources. Impact valuations were summed to yield a variable referred to as weighted cumulative impact (WCI), where the highest, positive WCI indicated least cumulative impact on resources. Scenarios were then ranked in terms of WCI. When ecological resources only were evaluated, the preregulation Flathead Lake scenario generated the highest WCI. However, when all resources were considered, scenarios ranked very differently but a preferred alternative was identified by virtue of its highest WCI. This interactive process of hydrology simulation and computation of cumulative impacts mediated resource conflicts and served as an important tool in deriving water management recommendations in the Flathead River Basin. The process may be useful elsewhere.

Medications of elderly institutionalized incontinent females

The purpose of the study was to explore drug use of elderly incontinent female nursing home residents, to identify potential drug--drug interactions, and to identify the number and categories of drugs taken having the potential to cause urinary incontinence. The medication administration records of 84 female residents were examined. The drugs were categorized by therapeutic classification as designated by the American Hospital Formulary Service. Potential drug--drug interactions were identified using The Hansten Drug Interaction Knowledge Base Program, a microcomputer version of Hansten's (1985) book Drug Interactions. Data were computer-coded and analysed using the Statistical Analysis System (SAS). A total of 454 drugs was taken by the 84 subjects, with an overall average of 5.40 drugs per person. The most frequently taken drugs were gastrointestinal drugs, central nervous system agents, electrolytic, caloric, and water balance drugs, and cardiovascular drugs. Fifty per cent (n = 42) of the subjects were identified as having 119 potential drug-drug interactions. Seventy per cent (n = 59) of the subjects were taking a drug having the potential to cause urinary incontinence. Suggestions for future research are presented.

Assessing the impacts of stream regulation in the flathead river Basin, Montana, U.S.A. I. Simulation modelling of system water balance

AbstractA Fortran‐based simulation model was written to predict water movement into and out of Flathead Lake. Since tributaries, the lake proper and downstream flows were either freeflowing or regulated by hydroelectric dams, it was necessary for the model to adjust simulated, regulated flows to account for predicted natural flows. Empirical input to the model consisted of daily discharge data or statistical summaries of data sets for an 80+ year period of record for gauging sites on major tributaries, the lake and its outlet river. The model produces graphical output of empirical observations or simulates lake levels and riverine flows on the basis of any selected period of the record. The model was successfully used to evaluate the feasibility of various water management scenarios to enhance or protect fish and wildlife and also permit various hydropower production quotas.

Stable isotope survey of the fresh water occurrences in Israel and the Northern Jordan Rift Valley

The stable isotope composition (Oxygen-18 and Deuterium) of the meteoric water cycle in Israel is presented. The survey comprises space and time variations of isotopic abundance in precipitation, surface and groundwater sources. Both the effect of the geomorphology on cloud evolution and of secondary evaporation from falling droplets under the cloud, determine the isotope composition of precipitation. In the mountainous aquifers the isotope composition, more or less, matches that of precipitation on the recharge areas. In the coastal plain and the inland valleys, on the other hand, we note further enrichment of heavy isotopic species in groundwaters relative to local precipitation. It is shown that the degree of aridity in different regions in the country is reflected in the isotopic composition, particularly in the value of parameter d = δ D − 8 δl8 O. The surface water survey includes that of the Upper Jordan river system. The isotope data are used to assess the hydrographical structure of the combined Jordan flow and the role that water loss by evaporation plays in the system's water balance. The isotope composition of the surface waters of the Dead Sea are also given.