How to simulate impact from pit latrines on water wells with MODFLOW - MT3DMS

Groundwater management takes into account quantity and quality aspects. Urban developement in emerging countries are not well match with the sanitation services and sometimes the water source is as well the wastewater disposal site.

This is a quick tutorial about the simulation of the a group of pit latrines impact on water well in Nigeria. Simulation done with MODFLOW and MT3DMS on transient conditions over 70 years.

This tutorial cover the following parts:

  • Review of the Boundary conditions
  • Set up of the transport model and species
  • Hydraulic (static and dynamic) parameters assigned
  • Time discretization for flow and transport
  • Output control
  • Groundwater flow regime
  • Contaminant transport simulation


Relevant topics

No reactions such as sorption or decay were considered.

Well pumps 0.25 l/s that averages 21.6 m3/day equivalent to water consumption of 270 inhabitants assuming a water demand of 80 l/s per person. This water demand is low because there is no water supply system.

Each pit latrine loss 70 l/d to the groundwater flow system. This rate is 8.1e-7m/s over a area of 1m x 1m.

Concentration of Nitrates at source was considered to be 1200 mg/l.



Example data

Download the original model data from this link:

Download the simulated model data from this link:

Saul Montoya

Saul Montoya es Ingeniero Civil graduado de la Pontificia Universidad Católica del Perú en Lima con estudios de postgrado en Manejo e Ingeniería de Recursos Hídricos (Programa WAREM) de la Universidad de Stuttgart con mención en Ingeniería de Aguas Subterráneas y Hidroinformática.

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