Analysis of catchment hydrology and nutrient loads for lakes Rotorua and Rotoiti

Abstract

A water and nutrient budget has been derived from lakes Rotorua and Rotoiti to complement an earlier report to the Lakes Water Quality Society that considered only internal (bottom sediment-derived) sources of nutrients for these two lakes. Twenty-six inflows to Lake Rotorua that have been monitored for varying periods are considered in this report. The combined annual mean discharge of these inflows varies between 12 and 17m3s-1 depending on the time period selected, which likely reflects long-term variations in rainfall and groundwater levels. Correlations of discharge in the Utuhina Stream with discharges of other major inflows were generally significant and reinforce the concept that discharges from individual streams respond in a synchronous fashion across the catchment of Lake Rotorua.