Valuation of Five Water-related Ecosystem Services in the Grand River Watershed.

English Abstract:

Valuation of ecosystem services can inform watershed management by analyzing the financial implications of land use changes. Here, we estimate the economic value of five water-related ecosystem services in the Grand River Watershed, Ontario, Canada. The watershed covers about 7000 km² of which about 80% is under agriculture. The watershed is undergoing rapid urbanization, with 81% of a population of 960,000 currently living in cities. The five services included in our analysis are water purification, water supply, water regulation, nutrient cycling and carbon sequestration. They are valuated using a methodology based on unit values of the services and land cover in the watershed. Four land use scenarios are considered that correspond to (1) pre-European settlement, (2) the year 1900, (3) the year 2014 and (4) a future land-use target based on the recommendations of Environment Canada. The scenarios illustrate the impact of agricultural intensification and urbanization on the ecosystem services within the watershed. The estimated monetary value of the ecosystem services dropped sharply by $178 million from pre-European settlement to the year 1900 due to deforestation and clearing of lands for cultivation. However, conservation and restoration practices have since then caused the value of the ecosystem services to rise again by $123 million.