Tuban Regency which has an important role as a supplier of irrigation water needs on agricultural lands. The objective of this study was to hydrochemically characterize of water from karst springs used as a source of irrigation water. The hydrochemical characterization carried out included the substance identification of the chemical type of water and the appraisal of its quality as an irrigation water source. The chemical type of water was determined by using the Piper trilinear diagram. The feasibility of water quality for irrigation was assessed based on potential salinity hazards and potential alkalinity hazards. Based on the results of this study it can be shown that the hydrochemical characteristics of water from karst springs in the study area were chemical type of Ca 2+ -Mg 2+ -HCO3 -, medium salinity hazard potential, and low alkalinity hazard potential. All water from karst springs in the study area are water with good quality for irrigation.

Dairy farms have potential to be organic sources (i.e., cow dung) for producing biogas. This paper presents a study on biogas production from a dairy farm in Pangalengan, South Bandung Area, Indonesia. We installed the Tenari Model biogas reactor with 4 m3 volume. The composition and amount of produced biogas were analyzed. Its effects on reducing water contaminants in Citarum River were studied by monitoring the reactor water effluent and mapping the river watershed. The produced biogas could supply daily cooking gas for the farm sufficiently.

The utilization of groundwater potential for irrigation has consequence for the high operational and maintenance costs of groundwater irrigation systems. One solution to these problems is the selection of high economic value crop types cultivated in groundwater irrigation lands. This study aims to determinate the alternative of types of agricultural crops that can be cultivated on groundwater irrigation land based on the quality of groundwater used as irrigation water based on the procedure: determination of groundwater quality index for irrigation, determination of types of agricultural crops based on criteria for tolerance to salt, adjustment of types of crop that have been determined with the criteria of high economic value crops, and adjustment to the types of crops that have been commonly cultivated by farmers in the local area. This procedure can be used as a solution to the absence of guidelines that can be used to determine alternative of types of agricultural plants on groundwater irrigation land. The results of this research showed the potential of ground water used as a source of irrigation water in the study site was dominated by groundwater with an index value of 70-85, where agricultural crops that could be recommended for planting were tolerant crops, moderately tolerant crops, and moderately sensitive crops to salt. The index value of groundwater quality for irrigation was mapped so obtained that zoning model of groundwater quality for irrigation and its suitability for the type of agricultural crops that can be cultivated.

Most of the population in the Jombang District area uses groundwater from dug wells and bor wells to meet their daily water needs. The quality of water from these wells was not always well controlled. The purpose of this research was to assess the quality of groundwater for drinking water and map its distribution patterns in the research location. The type of this research was development research with a descriptive research design. The groundwater quality index value for drinking water was determined based on the water quality index model and then mapped its distribution spatially in the study area. The spatial distribution of groundwater quality for drinking water in the study area, both during the rainy season and the dry season was dominated by areas with good and very good groundwater quality. The spatial distribution model of groundwater quality can be used as an indicator to assess the appropriateness of groundwater quality for drinking water in the research location.

Most of the population in the Jombang District area uses groundwater from dug wells and bor wells to meet their daily water needs. The quality of water from these wells was not always well controlled. The purpose of this research was to assess the quality of groundwater for drinking water and map its distribution patterns in the research location. The type of this research was development research with a descriptive research design. The groundwater quality index value for drinking water was determined based on the water quality index model and then mapped its distribution spatially in the study area. The spatial distribution of groundwater quality for drinking water in the study area, both during the rainy season and the dry season was dominated by areas with good and very good groundwater quality. The spatial distribution model of groundwater quality can be used as an indicator to assess the appropriateness of groundwater quality for drinking water in the research location.