This paper examines the nitrate concentration in the Aynalem and Mekelle groundwater sources of drinking water for Mekelle city. A total of 15 water samples taken from the two well fields showed that significant differences in nitrate concentration. The lowest concentration 6.6 mg/l and highest concentration 46.8 mg/l were found in the Aynalem groundwater wells. The highest nitrate concentration among the 10 wells of Aynalem was found downstream of the well field in an animal feedlot. On the other hand, with exception of one, Mekelle well located upstream from the main area of the city with a level of 11.7 mg/l, the downstream wells contained concentrations of 54.6, 65.7, 97.5, and 209 mg/l. These samples exceed the maximum nitrate level of 50 mg/l for drinking water, a guideline set by the World Health Organization (WHO, 1996). Such anthropogenic sources as animal feedlots and municipal wastes are considered possible sources for the high concentration of nitrates in the Mekelle wells. Further study is needed to identify the sources of nitrate pollution in both groundwater well fields concentrating on geology, precipitation, land topology, soil profile, and its health impact on users.

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The basic stochastic characteristics (moments) of annual precipitations in different parts of the world are investigated. Four moments, namely, mean (μ), standard deviation (σ), skewness (β), and kurtosis (γ) for the world's 10 districts and entire world itself have been computed. Their characteristics and mutual relations have been analyzed elaborately. The results of the analyses indicate the followings ; σ can be usually expressed by a gentle 2nd order function of μ, though in some districts the relationships are found to be linear. The shape of the frequency distribution of β has a mode ranging between 0.25 and 0.50, and has a right-hand tail. The shape of the frequency distribution of γ has a mode varying from 0 to 0.50, and has a right-hand tail. The shape of the stochastic distributions of annual precipitation has a right-hand tail and is expressed mainly by a Log-normal type equation. It is concluded that the stochastic distributions of annual precipitations of most countries of the world have longer right-hand tails and sharper peaks than those of normal distributions.

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A methodology to statistically analyze the function of runoff or flow regulations in a river basin and year-by-year change in its performance is proposed. The Shannon's information entropy is employed to evaluate the auto-entropies indicating temporal dispersion of occurrence of hydrological events ; rainfall in a catchment of a reservoir, inflow to the reservoir (i.e., runoff to the reservoir) and outflow from the reservoir. Using the Kullback-Leibler distance (often called the cross-entropy) to measure distance or discrepancy of a posterior distribution from a prior distribution, change in distribution between different two hydrological variables in rainfall-runoff process or in inflow-outflow process in analyzed. In order to investigate time-varying performance of hydrological regulation, each of these entropy statistics is expressed in a time evolutionary series. An emphasis is made that combined use of the auto-entropy and the cross-entropy is indispensable in a practical analysis. A sample application of the methodology is made to a dam reservoir and its catchment in Yasu River basin, Japan. The results suggest that during the last 50 years the runoff regulation function of the catchment has come to be regressive, and performance of the flow regulation in the reservoir has perceptibly been dependent on the skill of dam operators.

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India is a mega-biodiversity country with enormous variations in altitudinal and agro climatic zones varying from tropical in the south to temperate in the northern reaches. The overgrowing population and the water stress are calling for new approaches for water planning and management if escalating conflicts are to be avoided and environmental degradation is to be reversed. As India is using her water resources with growing intensity, poor rainfall increasingly leads to national water crises as water tables fall and reservoirs, wetlands and rivers get empty. Global warming could cause further changes, further variability and further uncertainty. Therefore, the purpose of this paper is to evaluate the economic feasibility of agriculture with rainwater harvesting and supplemental irrigation in arid and semiarid regions. We analyze overall pattern of rainfall variation for the period (1990-2001), annual evaporation and depleting groundwater resource of India and their impacts on agriculture, industry and domestic sectors. We conclude that the inadequate use and failure of arresting rainwater may cause agro-economic stagnation, which can be overcome by developing indigenous rainwater harvesting device with the participation of local communities to achieve the targeted growth rate. The traditional exercise of managing rainwater through artificial means may help to nullify the negative impacts of failure of monsoon in a particular year when it occurs to economy and ecology.

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To examine the behavior of DO from the viewpoint of formation and the break of density stratification, we continuously measured the water quality and micrometeorology of Lake Koyama at its deepest point of about 6 m from June to November in 2003. DO and EC in the surface and bottom layers, the vertical profile of the water temperature, the wind velocity and insolation were observed. As a result, DO in the bottom layer was lacking due to the formation of the thermal stratification in summer, and due to the saline stratification in a non-irrigation period after a large amount of sea water had flowed into Lake Koyama. The results also revealed a negative correlation between DO in the bottom layer and Wedderburn number W. Further analysis of the relationship between them indicated that anoxic water was generated due to the repression of the DO supply below surface layer under the stratification conditions of W>4.5, and that the anoxic state in the bottom layer could be eliminated by the generation of vertical circulation when the wind velocity of W<4.5, more than 4.0 m/s in summer and more than 10.0 m/s in the non-irrigation period, operated on the water area.

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To analysis the absorbing function of forest in the single pinus forest, we measured the concentration of pH, EC cation and anion about the collected rainfall, stemflow, throughfall, soil solution and streamwater. We also described a mechanisms and process that affect the rain water which flows into the soil, when it reaches forest area through the bodies of trees. The pH of stemflow (6.33) was figured out the lowest value, as pH of throughfall (5.83), also lower compared with that of rainfall (6.03). The EC of stemflow (110μ S/cm) and throughfall (63μ S/cm) showed a higher value, compared with that of rainfall (37μ S/cm). Density of Ca^<2+> showed the highest values among the cation and the results showed that Ca^<2+> concentration of stemflow and throughfall were affected by Ca^<2+> concentration of rainwater. Generally, concentration of anion was higher than that of cation, showing high values in the throughfall and soil solution.

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