Predicting Discharge From Agricultural Catchment to Support Land and Water Management in Singkarak Basin, West Sumatra

Limited hydrological data in Paninggahan sub catchment in Singkarak basin has resulted in inappropriate land management practices for farming system development. Predicting stream flow using an appropriate hydrological model is critical for a catchment with limited data recording. The present study has been conducted from January 2006 to December 2007. The objective of this study is to characterize hydrological condition of the catchment and to predict river flow for supporting design of landand water management options. To some extend, the study is to provide inputs in negotiation of farmers community with other stakeholders in the Singkarak basin. An automatic water level recorder (AWLR) and an automatic weather station (AWS) have been installed in the catchment to record hydro-meteorological data in order to calibrate hydrological model for predicting river flow. An instantaneous discharge model based on Geomorphological Instantaneous Unit Hydrograph (H2U) and a daily discharge model of GR4J were used to predict the river flow. The instanteneous hydrological data suggested that stream discharge sharply increased during onset rain and implying that the draining water was dominated by rapid flow. After peak storm has been reached, the water was slowly released to the river the one is typical hydrological process for disturbed catchments where rainfall water may no longer be retained in thecatchment. Application of both hydrological models in Paninggahan sub catchment during a period of March to April 2006 has given an appropriate result. The GR4J model has been calibrated and has given the value of similarity coefficient of 87.9%, while calibration of H2U model applied for storm event and has given the value of similarity coefficient of 96%. Thesucceed of predicting discharge using both models is valuable to support planning program in land and water management for farming system development in the Singkarak basin

Soil Destruction Level at Upstream of Cikapundung Sub Watershed on the North of Bandung Area

The upstream of Cikapundung sub watershed is the high land which is located on the North of Bandung Area. The soil is fertile, therefore the land is used as farming. The agriculture land is slope and the farmers have not applied the technology of conservation yet, as the result the soil susceptible to erosion. Consequently it decreases the productivity of land. The objectives of study were: (1) to evaluate erosion (value and risk erosion) at the use of land existing and (2) to investigate soil destruction level by erosion and its impact to productivity of land at upstream of Cikapundung sub watershed. The research used survey method. The data consisted of secondary data and primary data. The secondary data was collected through desk study, whereas primary data was collected through interviewed farmers, the soil observation, and soil sample analyses that is included the contain of sand, dust, and clay; C-organic; and nutrient content (N, P, K, and Ca) at Laboratory. The data analysis was done according to descriptive. The result showed that the most soil erosion was at the type of vegetable land use which use intensively at slope 25-40%.Value erosion roundabout 22.57-597.76 ton ha-1 year-1 or 0.33-8.79 cm. Level of destruction soil by erosion at upstream of Cikapundung sub watershed majority was medium critic (the upper soil was loss >75%) and spread at some units land. During five years, the impact of erosion decreased C-organic 60.05%, N 44.7%, P 52.3%, K 24.7%, and Ca 27.2%. Productivity Potato decrease 60%, whereas cabbage 40%

Analysis of Water Production Potencial Under Various Scenario in Paninggahan-Singkarak Watershed

Paninggahan watershed is the sub watershed of the Singkarak Lake watershed. It has a largest part of managed forest in the upstream and the change of landuse from forest to mixture garden increasing rapidly. The study on the change of discharge related to the landuse change is the main focus of this research. The result shows that hydrological characteristic of Paninggahan watershed is still good, with the domination of secondary forest covering 53% of the watershed. Therefore this watershed still has large amount of water reserve. The result of monitoring landuse change from year 1984-2007, indicating that the rate of forest decreasing was 66 ha year-1 and the increasing of mixture garden was 39 ha year-1. The result of characteristic simulation discharge showed that forest degradation will increase total volume of discharge to 1.3 m3 s-1, whereas minimum debit will progressively decrease till 0.2 m3 s-1. The knowledge of the influence of landuse change due to decreasing of debit in the watershed becomes guidance for the continous watershed development

Relationship Between Concentration and Discharge on Storm Events: Case Study at Cakardipa Catchment, Cisukabirus Subwatershed, Upper Ciliwung Watershed, Bogor, West Java

River nutrient loadings rates are frequently determined from discharge and hydrochemistry relationships using regression techniques. Unfortunately such methods as a conventional technique are inadequate for dealing with the problem such as differences in shape and direction of loop forming in individual and seasonal storms. Besides the relationships are nonlinear and time-dependent, they also varies from site to site. There is a currently method to study hysteresis between discharge and concentration of hydrochemistry. The relationship between discharge and solute concentration was investigated at Cakardipa catchment, Upper Ciliwung watershed, between the years of 2009-2010. The characteristics of the hysteresis loops were used to evaluate the temporal variation of the relative contribution to stream flow of source waters at Cakardipa Catchment including groundwater (CG), soil water (CSO), and rain water (CR). Chemical water analysis was carried out on 497 water samples on storm event. The chemical analysis of storm event of Februari 14, 2010 was carried out for the concentrations of K+, Ca2+, Mg2+, Na+, SiO2, SO42-NO3-, Cl-, and HCO3-. Results of the experiment showed that concentrations displayed circular hysteresis loops during the events, highlighting the complex relation among solutes and discharge during storm hydrographs. The solutes of K, Na, and Ca produced  concave curvature, anti-clockwise hysteresis loops, and positive  trend, so that classified as A2 loops with components ranking were CR> CG> CSO. .The solutes of Mg, SO4, NO3 assumed to come from groundwater produced convex curvature, clockwise hysteresis loops, and positive trend, indicating a concentration component ranking of CG > CR > CSO (C2 model). While Si and Cl produced clockwise hysteresis loops, indicating a concentration component ranking of CG> CSO> CR  which was C1 model.Keywords: Discharge, hydrochemistry, hysteresis, storm event[How to Cite: Heryani N, H Pawitan, MYJ Purwanto and K Subagyono. 2012. Relationship between Concentration and Discharge on Storm Events: Case Study at Cakardipa Catchment, Cisukabirus Subwatershed, Upper Ciliwung Watershed, Bogor, West Java. J Trop Soils 17 (1): 85-95. doi: 10.5400/jts.2012.17.1.85] [Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.1.85

Prediction of Drought Impact on Rice Paddies in West Java Using Analogue Downscaling Method

Indonesia consistently experiences dry climatic conditions and droughts during El Niño, with significant consequences for rice production. To mitigate the impacts of such droughts, robust, simple and timely rainfall forecast is critically important for predicting drought prior to planting time over rice growing areas in Indonesia. The main objective of this study was to predict drought in rice growing areas using ensemble seasonal prediction. The skill of National Oceanic and Atmospheric Administration's (NOAA's) seasonal prediction model Climate Forecast System version 2 (CFSv2) for predicting rice drought in West Java was investigated in a series of hindcast experiments in 1989-2010. The Constructed Analogue (CA) method was employed to produce downscaled local rainfall prediction with stream function (y) and velocity potential (c) at 850 hPa as predictors and observed rainfall as predictant. We used forty two rain gauges in northern part of West Java in Indramayu, Cirebon, Sumedang and Majalengka Districts. To be able to quantify the uncertainties, a multi-window scheme for predictors was applied to obtain ensemble rainfall prediction. Drought events in dry season planting were predicted by rainfall thresholds. The skill of downscaled rainfall prediction was assessed using Relative Operating Characteristics (ROC) method. Results of the study showed that the skills of the probabilistic seasonal prediction for early detection of rice area drought were found to range from 62% to 82% with an improved lead time of 2-4 months. The lead time of 2-4 months provided sufficient time for practical policy makers, extension workers and farmers to cope with drought by preparing suitable farming practices and equipments

Prediction of Drought Impact on Rice Paddies in West Java Using Analogue Downscaling Method

Indonesia consistently experiences dry climatic conditions and droughts during El Niño, with significant consequences for rice production. To mitigate the impacts of such droughts, robust, simple and timely rainfall forecast is critically important for predicting drought prior to planting time over rice growing areas in Indonesia. The main objective of this study was to predict drought in rice growing areas using ensemble seasonal prediction. The skill of National Oceanic and Atmospheric Administration's (NOAA's) seasonal prediction model Climate Forecast System version 2 (CFSv2) for predicting rice drought in West Java was investigated in a series of hindcast experiments in 1989-2010. The Constructed Analogue (CA) method was employed to produce downscaled local rainfall prediction with stream function (y) and velocity potential (c) at 850 hPa as predictors and observed rainfall as predictant. We used forty two rain gauges in northern part of West Java in Indramayu, Cirebon, Sumedang and Majalengka Districts. To be able to quantify the uncertainties, a multi-window scheme for predictors was applied to obtain ensemble rainfall prediction. Drought events in dry season planting were predicted by rainfall thresholds. The skill of downscaled rainfall prediction was assessed using Relative Operating Characteristics (ROC) method. Results of the study showed that the skills of the probabilistic seasonal prediction for early detection of rice area drought were found to range from 62% to 82% with an improved lead time of 2-4 months. The lead time of 2-4 months provided sufficient time for practical policy makers, extension workers and farmers to cope with drought by preparing suitable farming practices and equipments