A New Algorithm For The Grid Cell-Based Runoff Routing Model Based on Travel Time Concept

The grid cell-based routing model has recently been used to simulate direct runoff hydrographs at catchment scales. This study develops a flexible event-based runoff routing algorithm to simulate a direct runoff hydrograph (DRH). The experiment was based on the spatiotemporal inputs of a hydrological data set. The flexibility is based on the time step and grid cell size applied in the original STORE-DHM. Rainfall distribution was obtained using radar data adjusted by the measured point ground, while the runoff yield was determined using the NRCS-CN method. The parameter distribution was captured in the GIS environment as raster data formats. Furthermore, it was converted into ASCII data formats for scripting the routing algorithm using Matlab programming codes. The model algorithm was tested for storm events within two small study river systems in Yogyakarta, Indonesia. One event in each catchment was selected and calibrated to the observed hydrograph, treating the Curve Number (CN) and Manning coefficient (n) values as parameter calibrations. In the end, two events were selected for validation. The proposed routing model algorithm simulates DRHs of all selected events in the study areas with excellent performance. The Nash-Sutcliffe coefficient was greater than 0.75 for all DRH during validation, and the volume bias and peak discharge error were less than 25%. Keywords: Algorithm; Cell-based runoff routing; Travel time; GIS; Direct runoff hydrograph. Copyright (c) 2020 Geosfera Indonesia Journal and Department of Geography Education, University of Jember This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

KESESUAIAN HIDROGRAF SATUAN SINTETIK TERHADAP HIDROGRAF SATUAN TERUKUR(STUDI KASUS SUB SUB DAERAH ALIRAN SUNGAI PEDINDANG BAGIAN TENGAH)

A widely used method for analyzing river flow for flood forecasts is hydrograph unit. The hydrograph unit is a direct runoff hydrograph that can be created when there are AWLR record data, debit measurements and rainfall data. Synthetic Unit Hydrograph (SUH) is a unit hydrograph derived based on river data in the same watershed or nearby watershed but has the same characteristics, ie HSS Gama I, HSS Nakayasu, Limasan HSS, HSS Snyder and HSS SCS. Of the two hydrographs, there will be suitability of the hydrograph form that is going to be made. Sub territory of Pedindang River Basin has four flood incidents, namely, date 23-24 February 2016; March 2-3, 2016; March 3-4, 2016; and date 5-6 March 2016. In the analysis of each flood event, the peak discharge of synthetic unit hydrograph is very different from the peak discharge of the measured unit hydrograph. The average peak discharge of synthetic unit hydrograph occurs in the range of 2 or 3 hours, while the measured unit hydrograph of Pedindang River occurs in the range of 7 or 8 hours. In four flood events it is stated that, HSS Gama I approaches RMSE value (validation <10%) to HST form of Pedindang River with value: RMSE incidence I (23,601%); RMSE incidence II (16.315%); RMSE incidence III (50,400%); RMSE incidence IV (22.322%). With this result, it is stated that there is no synthetic unit hydrograph model that has compatibility with the measured unit hydrograph of Pedindang River.

Predicting Sedimentgraphs for a Small Agricultural Catchment

The key components of a sedimentgraph prediction procedure for small agricultural catchments are outlined in the paper. An instantaneous unit sedimentgraph (IUSG) based on the IUH and on a dimensionless sediment concentration distribution is developed, and used for transforming the sediment produced during a specified rainfall duration into a sedimentgraph. Rainfall-runoff-suspended sediment transport data from the River Dart basin, in Devon, UK, are used to evaluate several relationships for sediment yield estimation. The relationship between the lag time of the direct runoff hydrograph and the sedimentgraph is analysed, and the use of these lag times for estimating an IUSG (sediment routing) parameter is examined. The effectiveness of the proposed sedimentgraph prediction procedure is demonstrated by the successful regeneration of a measured sedimentgraph.