Heretaunga Steady-State Ground-Water Model / prepared by Tom Brooks.

"April 2006"

"Environmental Management Group Technical Report, Internal, Environmental Monitoring Section."

Includes bibliographical references (p. 51-52).

The Heretaunga Plains consists of about 5 to 7 primary aquifers that supply water to Hastings, Napier, Havelock North, Flaxmere, coastal, and inland communities. Ground water is used for public supply, agricultural, industrial, and domestic use. As surface waters have become nearly fully allocated, ground water has become an important supply, especially for drinking because it is relatively safe to drink without treatment. Ground water management requires hydrogeologic information and ground-water use to determine optimal benefits from ground-water development. Information needs include hydrogeologic and water use data. This report documents development of a steady-state ground-water model for the Heretaunga Plains. A steady-state model describes the ground-water basin at equilibrium; meaning that the pumping rates are constant and water levels are also constant--that this condition remains constant. Physical characteristics are as realistic as possible, and then matched against measured values, such as water level, to confirm the model is realistic. A computer model does not reproduce or replace the physical basin. It is instead, a mathematical model that generalises basin information to simulate real measured data, such as water levels. Therefore, simulations and predictions are most reliable for basin areas and least reliable at a specific point in the basin. Following steady-state model, transient models may be developed to show how changing pumping rates and other variables will change water levels and affect rivers. In this report, Council refers to Hawke's Bay Regional Council unless otherwise noted. Terms used in this report are defined on page vi. - Intro.