WebGIS development for base flow separation and recharge estimation

The basic flow rate is characterized by an important hydrological component being responsible for the estimation of the water recharge. Due to the difficulty of measurement, mathematical methods are used to calculate the flow separation. However, when hydrographic analysis is based on long historical series, the use of these methods becomes impracticable, making it necessary to use computational resources. A WebGIS (Web Geographical Information System) was developed for data selection and calculation of base flow separation, based on hydrological data from fluviometric stations located in the Taquari-Antas basin, located in the state of Rio Grande do Sul. A modified version of the Unified Process was used as a software development methodology. We used the MVC software architecture standard and the programming languages PHP 7.0, HTML5, JS and CSS3 for programmatic development of the constituent layers of the system. The hydrological data comes from the HIDROWEB portal, part of the National Information System on Water Resources (SNIRH), with hydrological information collected by the National Hydrometeorological Network (RHN) coordinated by the National Water Agency (ANA). The system facilitates the use of remote and distributed hydrological data, shared over the Internet, for various hydrological analyzes.

Variasi Temporal Kontribusi Aliran Dasar pada Mataair Epikarst di Kawasan Karst Gunungsewu, Indonesia

Aliran yang bergerak secara perlahan (infiltrasi) yang selanjutnya dikenal dengan aliran mantap atau aliran dasar (baseflow) merupakan satu-satunya pemasok air pada aliran bawah tanah pada bentuklahan karst ketika musim kemarau. kontribusi karakter aliran ini tentunya sangat berperan besar dalam mendukung penyediaan air bersih. Pemahaman terkait dengan karakteristik aliran dasar secara detail memiliki urgensi yang sangat tinggi untuk dikaji. Penelitian ini bertujuan untuk melakukan analisis temporal kontribusi aliran dasar pada mataair epikarst di Kawasan Karst Gunungsewu, Indonesia. Lokasi studi adalah Mataair Guntur yang menempati Sub-sistem Panggang. Data yang digunakan dalam penelitian ini meliputi data aliran dari Mataair Guntur selama satu tahun. Metode yang digunakan dalam penelitian ini adalah automated base flow separation by digital filtering. Hasil analisis menunjukkan bahwa konstribusi aliran dasar di Mataair Guntur adalah antara 79,57% sampai dengan 93,96%.

Revising the BFIHOST catchment descriptor to improve UK flood frequency estimates

The estimate of the base flow index (BFI) based on the Hydrology of Soil Types (HOST) classification, BFIHOST, provides a measure of catchment responsiveness. BFIHOST is used with other variables to estimate the median annual maximum flood (QMED) in the UK standard Flood Estimation Handbook (FEH) statistical method and is also an explanatory variable in ReFH2, the FEH design hydrograph package. The current estimates of BFIHOST are derived from a restricted linear model, and a number of issues in the catchment dataset have been identified since the original work in 1995. The BFI calculated through base flow separation tends to be underestimated in clay-dominated catchments, and the calculation technique performs poorly in ephemeral catchments or those with missing data. The pragmatic bounding of BFI coefficients for permeable soils overlying aquifer outcrops is also problematic for small catchments. This paper investigates alternative regression methods to improve base flow estimates using the HOST class data for 991 stations (compared to 575 in the original); beta regression was found to give the best performance. Combining multiple rare classes into single classes is also shown to improve performance. The new version of BFIHOST was applied to the QMED equation, showing improved performance.

Temporal Variations of Baseflow Contribution to Epikarst spring Discharge in Gunungsewu Karst Area, Indonesia

Flow moving slowly (infiltration), and known as steady flow or baseflow is the only supplier of water in underground flows in the form of karst fields during the dry season. Certainly, the character contribution of this flow plays a major role in supporting the supplier of clean water. Understanding related to the character of baseflow in detail has a very high urgency to be studied. This Research aims to do a temporal analysis of baseflow contributions on epikarst water springs in Gunungsewu Karst Area, Indonesia. The research takes place in Guntur Springs that occupy the hydrogeological subsystem. Data used in this Research includes flow data from Guntur Springs for one year. The method used in this Research is automated base flow separation by digital filtering. Results of the analysis show that baseflow contribution in Guntur Springs are between 79.57% and 93.96%.

Assessment of variability in runoff coefficients and their linkages with physiographic and climatic characteristics of two contrasting catchments

In the present study, long-term spatio-temporal variability in runoff coefficient (C) for different drainage areas of Upper Tapi basin, India, is analysed. The Upper Tapi basin is divided into two sub-catchments, Burhanpur and Purna, which are contrasting in nature in terms of their physiographic and climatic characteristics. The digital filter algorithm has been used to separate the base flow from observed streamflow for respective drainage areas. The sensitivity of the parameters involved in base flow separation is assessed by incorporating the hydrological and hydrogeological properties of individual drainage areas. The C values are then computed at different temporal scales, namely, daily, monthly, seasonal and annual, for different drainage areas. The effects of physiographic features such as topography, geology, soil type, and land use; and climatic features such as rainfall, temperature, and evapotranspiration, on the variability of C values are further investigated. The analyses reveal that Burhanpur sub-catchment (C = 0.39) yields higher C value compared to Purna sub-catchment (C = 0.11) at annual time scale. The C values clearly highlight the diversity in response of both sub-catchments, due to their distinct physiographic and climatic characteristics, and enabled us to study the variability in annual water balance of the basin.