LIFE URBASO aims to demonstrate that careful planning and adequate forest management of the up-slope areas of drinking water abstraction points is a requirement for maintaining raw water yield of high quality reducing sediment load, THMs and PTAs under the uncertainty of climate change.

To this end, URBASO will demonstrate this methodology in the Reserve of Biosphere of Urdaibai where 39 abstraction points are located in forested areas and 13 of them are in pine and eucalypt plantations.

A scarce resource

The scarcity and quality of drinking water are a matter of growing concern in industrialized countries. Overexploitation, changes in land use, pollution and climate change threaten drinking water sources (rivers and aquifers).

The water from rivers and streams collected in catchments is taken to purification plants before it is distributed. In Europe, chlorine is one of the most widely used raw water disinfectants.

However, it reacts with the natural organic matter (NOM) in the raw water, forming by-products such as carcinogenic trihalomethanes (THM). The amount and type of natural organic matter in the water comes from the basin itself and is largely determined by the vegetation, physical and biological processes in the soil, hydromorphology, climatic conditions and, in the case of forest basins, by forest management.

Therefore, the characteristics of raw water in surface water catchments can be modulated by forest management in the basin, directly influencing the necessary purification treatment and, as a consequence, the health of human beings.

Legislación

The EU Water Framework Directive (WFD) establishes that areas designated for the collection of water intended for human consumption must be protected by establishing a protection perimeter around them.

However, land uses within said protection perimeter are not regulated even though it has been verified that forest management strategies have a direct impact on the quantity and quality of water resources. The World Health Organization (WHO), in its Guidelines on the quality of drinking water, and the EU Drinking Water Directive set the maximum turbidity level for drinking water at 1 NTU. Wood extraction activities or soil preparation in forest areas carried out with machinery affect water flows, which translates into an increase in sediment load in streams (among others). The sediments carry NOM and reduce the clarity of the water, that is, they increase the turbidity.

Urdaibai

The water extracted from the Reserve presents the following baseline (2008-2018, EKUIS):

• NOM concentration measured as Dissolved Organic Carbon DOC = 3,83 mg L-1. No regulatory limit (directly linked with the generation of THMs).
• THM concentration = 46 μg L-1 ; But 10% of the analyses above the regulatory limit (Max concentration = 191 μg L-1) . Regulatory limit = 100 μg·L−1 (Spain)
• PTA: No regulation related in drinking water = No data. However, there is a need for policy that can increase the level of awareness of the possible risks of PTA.
• Turbidity = 23% of water samples above 1 NTU (Drinking water). Regulatory limit = < 1 NTU
• Suspended Sediments = 32-203 mg L-1 (average)

Goals

URBASO consortium will work to reach the following operational objectives:

• Develop a technical guide with a catchment delineation and characterization system to delimit the zone of intervention and operational forest management guidelines to protect water
• Implement the guidelines in the Reserve and demonstrate that these are useful to improve the raw water quality, reducing the amount of DOC (10%) and sediment load (25%) and consequently the use of disinfection products and the amount of THMs.
• Demonstrate that changes in land use provide a continuous and sufficient quantity (15% increase) of water for human consumption
• Demonstrate that bracken fern control reduces the amount of PTA in drinking water.
• Calculate the positive economic incentives for ecosystem service providers (forest owners) that could apply for a payment.
• Develop a contractual tool that might be used between forest owners, water suppliers and the Reserve of Biosphere for payments for ecosystem services.