The Nutrient Transport and Transformation model (NTT) is a generalized fate, speciation and transport model capable of simulating the movement of nutrients in the environment. The hydrologie model is an energy-driven, distributed parameter model that couples surface and ground waters. The vertical discretization consists of overland flow, perched saturated layer, root zone, percolation zone, and groundwater. The chemical model is based on the mass balances of nitrate, ammonium ion, organic nitrogen, humus material, organic phosphorus, phosphate, litter and biomass in the unsaturated zone and the groundwater. Geochemical processes affecting the nitrogen species mass balance that are included are nitrification, denitrification, plant uptake, mineralization, litter partition, humidification, decomposition, and biomass growth (uptake) and respiration. The NTT model was used to simulate the fate, transport and speciation of nitrogen through a corn riparian zone using data collected during the summer months of 1992. The NTT model was shown to be capable of simulating the hydrologic and biogeochemical processes occurring in riparian zones. The root mean square error between the simulated and observed nitrate concentration is 1 mg/l. The model can be used in the design of riparian buffers for nonpoint source pollution control.
The Watershed Nutrient Transport and Transformation (NTT‐Watershed) model is a physically based, energy‐driven, multiple land use, distributed model that is capable of simulating water and nutrient transport in a watershed. The topographic features and subsurface properties of the watershed are refined into uniform, homogeneous square grids. The vertical discretization includes vegetation, overland flow, soil water redistribution and groundwater zones. The chemical submodel simulates the nitrogen dynamics in terrestrial and aquatic systems. Three chemical state variables are considered (NO3‐‐, NH4+, and Org‐N). The NTT‐Watershed model was used to simulate the fate and transport of nitrogen in the Muddy Brook watershed in Connecticut. The model was shown to be capable of capturing the hydrologic and portions of the nitrogen dynamics in the watershed. Watershed planners could use this model in developing strategies of best management practices that could result in maximizing the reductions of nitrogen export from a watershed.
This paper presents an alternative water storage concept at lower sea-river interface vis-à-vis the conventional dam/reservoir storage scheme in the upper headwater region of a river basin. Two (2) estuary or coastal reservoir schemes are proposed to meet the future water demand of Johor Bahru and its vicinity. The low flow yields of a 98% reliability (or design 1:50-year return period) for both river schemes are also presented. A hydrological assessment is carried out to correlate the hydrometric variables, i.e. rainfall and streamflow. A long term 54-year streamflow record is adopted as input to the yield calculation. The reliable yields of 98% reliability criteria are in turn estimated based on a water balance or mass conservation. This new paradigmatic shift of reservoir storage location from headwater region to lower estuary/coastal interface can harness sufficient yield to meet the future demand of Johor Bahru and vicinity.
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