Dependable flow modeling in upper basin Citarum using multilayer perceptron backpropagation

To determine the amount of dependable flow, a hydrological approach is needed where changes in rainfall become runoff. This diversification is a very complex hydrological phenomenon. Where this is a nonlinear process, with time changing and distributed separately. To approach this phenomenon, an analysis of the hydrological system has been developed using a model which is a simplification of the actual natural variables. The model is formed by a set of mathematical equations that reflect the behavior of parameters in hydrology. Modeling in this case uses artificial neural networks, multilayer perceptron combined with the backpropagation method is used to study the rainfall-runoff relationship and verify the model statistically based on the mean square error (MSE), Nash-Sutcliffe Efficiency (NSE) and correlation coefficient value (R2). Of the three models formed, model 3 provides optimum results with correlation levels using NSE per month as follows, in Cikapundung Sub-Basin NSE = 0,990703, R2 = 0,995008, and MSE = 0,00014443, while in Citarik Sub-Basin NSE = 0.9500, R2 = 0.97592, and MSE = 0.0010804 . From these results it can be seen that ANN has a fairly good ability to replicate random discharge fluctuations in the form of artificial models that have almost the same fluctuations and can also be applied in rainfall runoff modelization even though the results of the test results are not very accurate because there are still irregularities

The effect of land uses to change on infiltration capacity and surface runoff at latung sub watershed, Padang City Indonesia

Changes in land use in the Air Dingin watershed (DAS) area in Padang City, Indonesia, lead to a decrease in rainwater infiltration volume to the ground. Some land use in the Latung sub-watershed decrease in infiltration capacity with an increase in surface runoff. This research aims to determine the effect of land-use changes on infiltration capacity and surface runoff. Purposive sampling method was used in this research. The infiltration capacity was measured directly in the field using a double-ring infiltrometer, and the data was processed using the Horton model. The obtained capacity was quantitatively classified using infiltration zoning. Meanwhile, the Hydrologic Engineering Center - Hydrology Modeling System with the Synthetic Unit Hydrograph- Soil Conservation Service -Curve Number method was used to analyze the runoff discharge. The results showed that from the 13 measurement points carried out, the infiltration capacity ranges from 0.082 - 0.70 cm/minute or an average of 0.398 cm/minute, while the rainwater volume is approximately 150,000 m3/hour/km2. Therefore, the soil infiltration capacity in the Latung sub-watershed is in zone VI-B or very low. This condition had an impact on changes in runoff discharge in this area, from 87.84 m3/second in 2010 to 112.8 m3/second in 2020 or a nail of 22.13%. Based on the results, it is concluded that changes in the land led to low soil infiltration capacity, thereby leading to an increase in surface runoff.

Water dynamics at the urban soil-atmosphere interface—rainwater storage in paved surfaces and its dependence on rain event characteristics

Purpose The surface store governs the rainwater partition, e.g., water storage and evaporation on paved surfaces, especially for low-intensity and low-sum rain events, which account for the greatest part of the total rainfall in a temperate climate city like Berlin, Germany. The surface store S is a fixed value, dependent on surface relief and pore system characteristics. Contrary, in this study, the surface storage was assumed to depend also on the rain intensity, thus being variable from event to event. Materials and methods The surface store filling dynamics for dense (DP), porous (PP), and highly infiltrative (IP) paving materials were studied in a rainfall simulator. Irrigation intensities p ranged from 0.016 to 0.1 mm min−1 which represent the 25 to 88% quantiles of the rain event distribution in Berlin, Germany (1961 to 1990). Results and discussion Three surface stores can be separated: storage until initial runoff, Sf, at maximum filling, Sm, and for steady-state runoff, Seq—all of them can be regarded as effective stores depending on the aim of its use. The equilibrium store varies from 0.2 to 3 mm for DP, PP, and IP for the investigated rainfall intensities. Conclusions For all pavers, the surface store depends on rainfall intensity, which was shown experimentally and confirmed by numerical simulation of the infiltration. We introduce a simple and robust method to describe Sf, Sm = f(p) for different pavers. Pavers can evaporate a multiple of their surface store per day, depending on the rainfall distribution, which implicates the need for high temporal resolutions in urban hydrology modeling. Pavers can evaporate a multiple of their surface store per day, depending on the rainfall distribution. That implicates the need for high temporal resolutions in urban hydrology modeling.

An Ensemble Climate-Hydrology Modeling System for Long-Term Streamflow Assessment in a Cold-Arid Watershed

Climate change can bring about substantial alternatives of temperature and precipitation in the spatial and temporal patterns. These alternatives would impact the hydrological cycle and cause flood or drought events. This study has developed an ensemble climate-hydrology modeling system (ECHMS) for long-term streamflow assessment under changing climate. ECHMS consists of multiple climate scenarios (two global climate models (GCMs) and four representative concentration pathways (RCPs) emission scenarios), a stepwise-cluster downscaling method and semi-distributed land use-based runoff process (SLURP) model. ECHMS is able to reflect the uncertainties in climate scenarios, tackle the complex relationships (e.g., nonlinear/linear, discrete/continuous) between climate predictors and predictions without functional assumption, and capture the combination of snowmelt– and rainfall–runoff process with a simplicity of operation. Then, the developed ECHMS is applied to Kaidu watershed for analyzing the changes of streamflow during the 21st century. Results show that by 2099, the temperature increment in Kaidu watershed is mainly contributed by the warming in winter and spring. The precipitation will increase obviously in spring and autumn and decrease in winter. Multi-year average streamflow would range from 105.6 to 113.8 m3/s across all scenarios during the 21st century with an overall increasing trend. The maximum average increasing rate is 2.43 m3/s per decade in October and the minimum is 0.26 m3/s per decade in January. Streamflow change in spring is more sensitive to climate change due to its complex runoff generation process. The obtained results can effectively identify future streamflow changing trends and help manage water resources for decision makers.

SHaKTI: Subglacial Hydrology and Kinetic Transient Interactions v1.0

Subglacial hydrology has a significant influence on ice sheet dynamics, yet remains poorly understood. Complex feedbacks play out between the liquid water and the ice, with constantly changing drainage geometry and flow mechanics. A clear tradition has been established in the subglacial hydrology modeling literature of distinguishing between channelized (efficient) and distributed (inefficient) drainage systems or components. Imposing a distinction that changes the governing physics under different flow regimes, however, may not allow for the full array of drainage characteristics to arise. Here, we present a new subglacial hydrology model: SHaKTI (Subglacial Hydrology and Kinetic Transient Interactions). In this model formulation, a single set of governing equations is applied over the entire domain, with a spatially and temporally varying transmissivity that allows for representation of the wide transition between turbulent and laminar flow, and the geometry of each element is allowed to evolve accordingly to form sheet and channel configurations. The model is implemented as a solution in the Ice Sheet System Model (ISSM). We include steady and transient examples to demonstrate features and capabilities of the model, and we are able to reproduce seasonal behavior of the subglacial water pressure that is consistent with observed seasonal velocity behavior in many Greenland outlet glaciers, supporting the notion that subglacial hydrology may be a key influencer in shaping these patterns.

STUDI KOMPARASI PEMODELAN 1-D (SATU DIMENSI) DAN 2-D (DUA DIMENSI) DALAM MEMODELKAN BANJIR DAS CITARUM HULU

Pengelolaan Daerah Aliran Sungai (DAS) yang tidak baik akan menimbulkan kerusakan. Salah satu indikasi bahwa suatu DAS mengalami kerusakan adalah terjadinya banjir. Pada saat kondisi jumlah air sungai melebihi kapasitasnya atau menjadi terlalu banyak maka terjadi banjir yang diakibatkan oleh luapan sungai. Faktor dari peristiwa alami seperti intensitas curah hujan yang tinggi merupakan penyebab terjadinya banjir, ditambah lagi dengan faktor aktifitas manusia. Salah satu cara untuk mengantisipasi bencana banjir adalah dengan memprediksi terjadinya banjir tersebut. Studi ini bertujuan untuk menganalisis perbedaan hasil yang diperoleh pada pemodelan 1-D dan 2-D terkait akurasi hasil untuk analisis lanjutnya. Keterbatasan data yang diperoleh dan ketepatan pemilihan metode pemodelan banjir akan mengurangi keakuratan hasil pemodelan dalam memprediksi banjir. Secara garis besar metode pemodelan banjir terdiri dari dua bagian yaitu pemodelan hidrologi (hydrology modeling) dan pemodelan hidrolika (hydraulic modeling). Pemodelan hidrologi pada daerah studi yaitu DAS Citarum Hulu, Jawa Barat menggunakan hidrograf metode SCS dan Snyder dengan bantuan software HEC-HMS, sedangkan pemodelan hidrolika menggunakan bantuan software HEC-RAS. Hasil yang diperoleh akan dilakukan kalibrasi dan verifikasi. Pemodelan dengan HEC-RAS 5.03 dianalisis untuk model 1-D dan 2-D, kemudian kedua data komparasikan untuk menganalisis perbedaan atau rentang hasil yang diperoleh terkait pemilihan metode pada DAS yang lain. Kata Kunci : Banjir, Citarum, Flood Modeller, Pemodelan, Sungai Deli ABSTRACT Management of Watersheds (DAS) will cause damage if one indication that a watershed is damaged is the occurrence of floods. When the condition of the river water exceeds its capacity or becomes too much, there will be flood caused by the river flood. Factors of natural events such as high rainfall intensity is the cause of flooding, coupled with the factor of human activity. One way to anticipate flood disaster is to predict the occurrence of the flood. This study aims to analyze the differences in results obtained in 1-D and 2-D modeling on yield accuracy for further analysis. Limitations of the data obtained and the accuracy of selection of flood modeling methods will reduce the accuracy of the modeling results in predicting flooding. The method consists of two parts, hydrology modeling and hydraulic modeling. Hydrology modeling in the study area is upper Citarum Watershed, West Java using hydrograph of SCS and Snyder method with HEC-HMS software, while hydraulic modeling using HEC-RAS software. The results obtained will be calibration and verification. Modeling with HEC-RAS 5.03 was analyzed for 1-D and 2-D models, then the two comparative data to analyze the difference or range of results obtained related to the selection of methods in other watersheds Keywords: Citarum, Deli River, Flood, Modelling

Scale effect challenges in urban hydrology highlighted with a distributed hydrological model

Nowadays, hydrological models are extensively used in urban water management, future development scenario evaluation and research activities. A growing interest is devoted to the development of fully distributed and grid based models, following the increase of computation capabilities. The availability of high resolution GIS information is needed for such models implementation to understand flooding issues at very small scales. However, some complex issues about scaling effects still remain a serious issue in urban hydrology. The choice of an appropriate spatial resolution is a crucial problem, and the obtained model performance depends highly on the chosen implementation scale. In this paper we propose a two step investigation framework using scaling effects in urban hydrology. In the first step fractal tools are used to highlight the scale dependency observed within distributed data used to describe the catchment heterogeneity, both the structure of the sewer network and the distribution of impervious areas are analyzed. Then an intensive multi-scale modeling work is carried out to understand scaling effects on hydrological model performance. Investigations were conducted using a fully distributed and physically based model, Multi-Hydro, developed at Ecole des Ponts ParisTech (Multi-Hydro (2015)). The model was implemented at 17 spatial resolution ranging from 100 m to 5 m. Results coming out from this work demonstrate scale effect challenges in urban hydrology modeling. In fact, fractal concept highlights the scale dependency observed within distributed data used to implement hydrological models. Patterns of geophysical data change when we change the observation pixel size. The multi-scale modeling investigation performed with Multi-Hydro model at 17 spatial resolutions confirms scaling effect on hydrological model performance. Results were analyzed at three ranges of scales identified in the fractal analysis and confirmed in the modeling work. In the meantime, this work also discussed some issues remaining in urban hydrology modeling such as the availability of high quality data at higher resolutions and, model numerical instabilities as well as the computation time requirements. But still the principal findings of this paper allow replacing traditional methods of model calibration by innovative methods of model resolution alteration based on the spatial data variability and scaling of flows in urban hydrology.