Eko Haryono

Diffuse flow characteristics and their relation to hydrochemistry conditions in the Petoyan Spring, Gunungsewu Karst, Java, Indonesia

This study was conducted on the Petoyan Spring, one of the most important springs in the western part of Gunung Sewu Karst, Java, Indonesia. The main purpose of the study is to define the diffuse flow characteristics of the spring. It also focuses on identifying the relationship between the diffuse flow proportion and several hydrochemical parameters to provide a better aquifer characterization. Water-level monitoring and discharge measurements were conducted over an eight months period in order to define the discharge hydrograph. The calculation of recession constants, including the diffuse flow (Kb), fissure flow (Ki), and conduit flow (Kc), was done by selecting several flood hydrograph events. Furthermore, the base flow-separation analysis was conducted to determine the diffuse flow proportion throughout the research period. Water sampling for hydrogeochemical analysis was taken every week and every hour for two selected flood events. A bivariate plot analysis between the diffuse flow proportion and certain hydrochemical parameters was made in order to describe the hydrogeochemical processes. The results showed that the diffuse- flow significantly dominates the spring discharge during non-flooding and flooding recession periods. Conversely, during the rising limb period, the diffuse proportion decreased drastically due to the conduit flow supply. This fact was also supported by the high Kb and short Tp (time to peak) and Tb (time to base flow) values. Hydrogeochemically the correlation between the diffuse flow proportion and major dissolved elements during the flood recession periods was strong because the conduit flow domination was replaced by the diffuse flow, causing the domination of water-rock interaction. According to the diffuse flow and its relation to its hydrochemistry, it is apparent that small fractures in the Petoyan Spring aquifer still provide good storage for the diffuse flow, even though the conduit fracture has already been developed.

Characterization of recharge and flow behaviour of different water sources in Gunung Kidul and its impact on water quality based on hydrochemical and physico-chemical monitoring

Karst aquifers are important water resources but highly vulnerable due to their heterogeneous and complex characteristics. Various hydrological aspects (recharge, flow behaviour) have to be known in detail to develop a sustainable concept for water collection, distribution and treatment. In the karst area of Gunung Sewu (Java, Indonesia) such a concept was to be implemented within a German–Indonesian joint IWRM project. The basic hydrogeological conditions and water quality aspects were characterized on a regional scale through hydrochemical monitoring of springs, wells, subsurface and surface rivers. More detailed information about the recharge, flow and storage behaviour was obtained from high resolution monitoring of T, EC and discharge in one large underground river system. The water quality is well below any guideline values with regard to inorganic pollutants during dry season. During rainy season, dissolved Al concentrations are frequently above the Indonesian guideline value. Slow matrix flow is the most important recharge component during dry season, thus assuring the year-round water availability in the subsurface karst. During rainy season, quick infiltration of the surface water is a dominant recharge component. Rapid response of discharge, T and EC to heavy rain suggests the presence of point recharge that feeds a highly karstfied conduit system with fast conduit flow and short transit time of water. The strong variations in discharge and hydrochemistry are particularly challenging for technical water usage and treatment facilities. Piston flow is indicated to be the third important flow component and is induced by heavy rainfall.

Spatial and temporal hydrochemistry variations of karst water in Gunung Sewu, Java, Indonesia

A hydrogeochemical study was conducted in the Gunung Sewu Karst, Java Island, Indonesia. The main objective of this study is to describe the spatial and temporal variations of hydrochemistry that occur in the central and western parts of Gunung Sewu. Discharge measurements for a one-year period are taken in some karst springs or underground rivers to define their discharge hydrograph. Furthermore, baseflow separation analysis was conducted to determine the base flow percentage throughout the year. Water sampling for hydrogeochemical analysis was taken every month to represent the dry and rainy season conditions. To describe the hydrogeochemical processes, a scatter plot analysis with a small sample size was conducted. The results showed that the hydrochemistry of karst water in the study area has different characteristics spatially and temporally. Within the dry season, the dominant hydrogeochemical process is water–rock interaction (precipitation of calcite mineral), indicated by achieving the maximum level of Ca2+, HCO3−, electrical conductivity, base flow percentage, and SI calcite, with the lowest level of log

The present and the Archaic River Valley morphology and groundwater condition in the Plaosan Temple complex Central Java-Indonesia

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The Nature of Carbon Flux in Gunungsewu Karst, Java-Indonesia

PCO2 in the water. In addition, the dry season hydrochemistry is characterized by a strong relationship between electrical conductivity–calcium/bicarbonate, base flow percentage-discharge, base flow percentage-SI calcite, and SI calcite-log

Potency of Curculigo capitulata and Curculigo latifolia Fruit Based on Nutrient Content (a Case for Preservation Need in Kebonharjo)

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