D. S. Arya

Modeling of urban growth dynamics and its impact on surface runoff characteristics

Abstract Modeling urban growth and generating scenarios are essential for studying the impact and sustainability of an urban hydrologic system. Urban systems are regarded as complex self-organizing systems, where the dynamic transitions from one form of landuse to another occur over a period of time. Therefore, a modeling framework that captures and simulates this complex behavior is essential for generating urban growth scenarios. Cellular Automata (CA)-based models have the potential to model such discrete dynamic systems. In this study, a constraint-based binary CA model was used to predict the future urban growth scenario of the city of Roorkee (India). A hydrologic model was applied on the simulated urban catchment to study its hydrologic response. The Natural Resources Conservation Service Curve Number (NRCS-CN) method, which is suitable for ungauged urban watersheds, was adopted to determine the impact of urban growth on the quantity of storm water runoff over a period of time. The results indicate that urban growth has a linear relationship with peak discharge and time to peak for the catchment under investigation.

Design Flow and Stage Computations in the Teesta River, Bangladesh, Using Frequency Analysis and MIKE 11 Modeling

A case study was conducted in the Teesta subcatchment in Bangladesh for determining design flood flows and corresponding flood stages for different return periods using frequency analysis and MIKE 11 model. Different distribution functions of frequency analysis were tested for their goodness of fit. The observed discharge data at Kaunia on the river Teesta were used for estimation of design flood. The Pearson type-III distribution was found best fitted by the Kolmogorov-Smirnov, D-index, and L-moment diagram ratio tests, and accordingly 25-, 50-, and 100-year return period design floods were computed. The river network of Teesta River was extracted from SRTM 90-m digital elevation model. The river network of Teesta subcatchment was then simulated by MIKE 11 rainfall-runoff Nedbor-Afstromnings-Model (NAM) and HD model. The resultant time series of river stage was then compared with corresponding observed values. From the model, a stage-discharge relationship ( Q-h ) curve and respective equation were devel...

Identification and Classification of Key Variables and their Role in Environmental Impact Assessment: Methodology and Software Package Intra

There is, as yet, no proven methodology to enable, objectively,the identification of key parameters out of a large number one normally encounters during any EIA. As EIA is a costly and time-consuming exercise, it is necessary to separate the man from the boys – so to speak – in order to optimize costs andefforts.In this paper a methodology for distinguishing the moreimportant parameters from the less important ones, developed byus, is described. The methodology aims at identifying andshortlisting the key parameters which ought to be studied in agiven EIA situation, thereby helping in reducing time, effort,and cost of EIA. With this methodology a system structure is developed whichgives hierarchical pattern of inter-parameter interaction, andreveals several distinguishing features of each parameter. Asoftware package INTRA (INTer-parameter Relationship Analysis)based on this methodology, has been developed. The paper alsodescribes a case study in which INTRA has been used to study theenvironmental impacts of urbanization of a typical third worldtown (Roorkee).

Impact of ENSO on River Flows in Guyana

The El Niño Southern Oscillation (ENSO) phenomenon is a natural part of the global climate system resulting from the interactions between large-scale ocean atmospheric circulation processes in the equatorial Pacific and Indian Oceans. In Guyana, for all the adverse weather and extreme hydrological events, the blame goes to El Niño or La Niña. This paper investigates the relationship between ENSO and three Guyanese river flows; the Demarara, Essequibo and Mazaruni. This work sheds some light on the effects of this phenomenon on these river flows which may be useful for the adaptation policies dealing with the impacts of ENSO.

Potential Impact of Climate Change on Rainfall Intensity-Duration-Frequency Curves in Roorkee, India

Intensification and frequency of hydrologic events are attributed to climate change and are expected to increase in coming future. Intensity-Duration-Frequency (IDF) curves quantify the extreme precipitation and are used extensively to assess the return periods of rainfall events. It is expected that climate change will modify the occurrence of extreme rainfall events. Thus a need of updating IDF curves arises under the climate change scenario. This paper aims at updating the IDF curves for a typical Indian town using an ensemble of five General Circulation Models (GCMs) for all the Representative Concentration Pathways (RCP) scenarios. Sub-daily maximum intensities (15-, 30-, 45-, 60-, 120-, and 180xa0min) were obtained from the observed records. Equidistance quantile method was used to study the relationships between the historical and projected GCM data, and the historical GCM and observed sub-daily data. This relationship was used to obtain projected sub-daily intensities. The IDF curves were developed using observed and projected data. Analysis of the curves indicated increase in precipitation intensities for all the RCP scenarios. It was also found that intensities of all return periods increases with intensifying RCP scenarios. The variation in the intensities across the GCMs was attributed to the driving forces considered in a particular GCM.

Development of the Jamuneswari Flood Forecasting System: Case Study in Bangladesh

AbstractA flood forecasting system has been developed using MIKE11 river-modeling software modules rainfall-runoff (RR) [or Nedbor-Afstromnings model (NAM)], hydrodynamic (HD), and flood forecasting (FF) for the Jamuneswari river catchment of the northwestern part of Bangladesh. The 3-arc second shuttle radar topography mission (SRTM) digital elevation model (DEM) version 4.0 and the D8 method of ArcGIS9.3 have been used to delineate river network and catchment bounderies, which are required for MIKE 11 model setup. The European Centre for Medium-Range Weather Forecast (ECMWF) model-forecasted rainfall data have been used in MIKE 11 NAM-HD modules to increase the forecast lead time to 72xa0h. Errors in forecast results have been assessed by computing efficiency index, coefficient of correlation, volume error, peak error, and peak time error. Integration of the MIKE 11 HD module with the MIKE NAM module has improved the result by 10.84% for efficiency index, 20.7% for volume error, 25.61% for peak error, and...

Improved Planning Model for Canal Scheduling of Rotational Irrigation

AbstractThis paper depicts some limitations of a canal scheduling model that gives water delivery schedules for a rotational distribution system using the concept of weights based on the irrigation performance indicators. The indicators used are equity, adequacy, timeliness, and location (based on the convenience of gate operator). Possible improvements in the model are suggested to remove the drawbacks of untimely water supplies to some of the distributaries, poor supply to demand ratios, and the inconveniences faced by the gate operator in opening some of the distributaries. This proposed model is designated as the improved planning model for canal scheduling. Based on this, a canal operational schedule is recommended for the whole irrigation distribution system for the kharif season, which is more effective in fulfilling the multiple objectives of irrigation.

A Proposed Decision Support System for River Water Quality Management in India

The growing concern for river water pollution in India is witnessing several initiatives from nodal agencies in terms of water pollution control. In a similar context, a need for a supportive platform is envisaged that takes care of management perspectives, feasible for Indian conditions. In this paper the most generic DSS has been proposed that caters to the requirement of regulatory authorities. In its prototype scale of application to improving water quality, at user defined water quality criterion, the system is capable of allocating waste loads to point sources, while liberating the user from writing the input files for simulation and management models. The system is designed for PC-Windows environment with minimal system requirements in terms of models viz., QUAL2E water quality model and LINDO optimizing package, interfaced using SQL Server 2000 Data base Management System. While the most expedient approach of treatment at source towards water quality management in India was addressed by the system, the example run of the DSS indicated a need of including other management options for comprehensive quality management.

Developmental trends and their environmental impact in a typical central Indian town with special reference to Roorkee

The roots of present-day environmental problems affecting urban centres can be traced to their unplanned and rapid development, specially during the last few decades. An understanding of the precise nature of the dynamics of urban growth and its impact on the environment can help us in evolving strategies for better environmental and developmental planning (Paul et al., 1976). The present study, using the town of Roorkee (Uttar Pradesh, India) as a model, is one such attempt (Arya, 1991).

IRRIGATION PERFORMANCE IMPROVEMENT BY NON- STRUCTURAL MEASURES - A CASE STUDY FROM BANGLADESH

Potential performance of an irrigation project rarely attains its optimum level. The causes may be deterioration of physical condition of infrastructures, non-optimal operation of water control structures, inadequate conveyance of the irrigation system, excess withdrawal at upstream, lacking of optimal managerial and operational irrigation schedule. The effect of these results reduced crop-yield. The Meghna-Dhonagoda Irrigation Project (MDIP) is one of the aspirant irrigation projects in Bangladesh. The Project area comprises 17584 hectares of which 14602 hectares are cultivable. Irrigation water is supplied by withdrawing water from river by two pump houses. The Project was implemented during 1978 to 1887. Since inception only 50% of irrigation performance was receiving from more or less reliable supply of water and the same was declining over the years. Among all constraints it was conceptualized that the practiced irrigation schedule and operational management were the main obstacles to attain its optimum result. It is found that over the total crop period the Crop Water Requirement (CWR) is considered as fixed depth of 265 mm/month, which causes the scarcity of water in the land preparation and flowering stages, on the other hand misuse of water in the matured and growing stages. The causes of this type of irrigation schedule is due to physically based problem of irrigation canal system, pump operation, land use and variety of cropping pattern in the same season. Since 2000, peoples participation, a non-structural measure has been practicing to overcome these problems. By peoples participation irrigation performance was improved up to some extant (up to 70%). To attain the maximum potential irrigation performance, a new strategy of staggered cropping pattern, is recommended. Another non-structural measure is Application of Decision Support System (DSS) for improvement of irrigation performance. A GIS based DSS, MDIP-DSS, developed by Bangladesh Water Development Board (BWDB) in 2000, which integrates with MIKE-11 HD and MIKE-SHE models. With this MDIP-DSS, an optimised scenario has been simulated for pump operation and gate operation of the water control structure for MDIP. Analysis shows the best simulation can increase the dependable irrigation index up to 82% and the highest average index up to 92% for high yielding variety Boro rice in MDIP. Combination of both of these non-structural measures will give more improvement of the irrigation performances in any irrigation project.