A simple stacked ensemble machine learning model to predict naturalized catchment hydrology and allocation status

TL;DR

This paper introduces a simple stacked ensemble machine learning model that accurately predicts naturalized hydrology and water allocation status in New Zealand catchments, aiding sustainable water management.

Contribution

A novel, straightforward ensemble model that effectively predicts hydrological and allocation status in over-allocated catchments, supporting water resource management decisions.

Findings

Model achieves R2 > 0.8 for key hydrological predictions

Identifies varying risk levels in water resource management

Can be applied to other regional catchments worldwide

Abstract

New Zealand legislation requires that Regional Councils set limits for water resource usage to manage the effects of abstractions in over-allocated catchments. We propose a simple stacked ensemble machine learning model to predict the probable naturalized hydrology and allocation status across 317 anthropogenically stressed gauged catchments and across 18,612 ungauged river reaches in Otago. The training and testing of ensemble machine learning models provides unbiased results characterized as very good (R2 > 0.8) to extremely good (R2 > 0.9) when predicting naturalized mean annual low flow and Mean flow. Statistical 5-fold stacking identifies varying levels of risk for managing water-resource sustainability in over-allocated catchments; for example, at the respective 5th, 25th, 50th, 75th, and 95th percentiles the number of overallocated catchments are 73, 57, 44, 23, and 22. The proposed model can be applied to inform sustainable stream management in other regional catchments across New Zealand and worldwide.