Understanding and Acting: Community

Transcription

1 Understanding and Acting: Community Catchment t Management age e at Loweswater Lisa Norton, Claire Waterton, Judith Tsouvalis, Stephen Maberly, Linda May, Alex Elliott, Nigel Watson, John Rockliffe, Leslie Webb, and the Loweswater Care Project.

2 Introduction to study Loweswater is a small catchment t ~ 8km in the Lake District i t National Park Blue green algal blooms resulting from high Phosphorus

3 Ecological research at the catchment scale Linking land use and water Landscape structure Biodiversity on land Natural England/Defra (CAP) Farmers National Trust Environment Agency (WFD) Land management Nutrients on land Economic viability Community Nutrients lost to water Lake structure Biodiversity in water Lake District National Park Authority

4 Modelling strategy Collect farm data management scenario data To understand how what is done in the catchment is related to the algal blooms in the lake Collect rainfall & flow data nutrient budget (PLANET) Land cover Calibrate rainfall/runoff model (GWLF) Adjust for soil P deficit Add P losses from septic tank (as point or diffuse) Local weather Calculate farm nutrient excess Calculate nutrient runoff concentrations (= nutrient t excess/flow) Generate daily nutrient inputs to lake (GWLF) Predict lake response (PROTECH) Generate daily runoff values Status quo Scenario testing

5 Calculate nutrient excess on each farm 1. Collect data from farmers 2. Enter data into PLANET (Planning Land Application of Nutrients for Efficiency and the environment) 3. Calculate phosphorus and nitrogen balance for each farm, based on imports and exports of : 1. Fertiliser 2. Livestock 3. Feedstuffs 4. Bedding 5. etc. 1&2 1. Predict nutrient excess on each farm Collect farm data management scenario data nutrient budget (PLANET) Land cover Collect rainfall & flow data Calibrate rainfall/runoff model (GWLF) 3 & 4 Adjust for soil P deficit Add P losses from septic tank (as point or diffuse) Local weather Calculate farm Generate daily nutrient excess runoff values Calculate nutrient runoff concentrations (= nutrient excess/flow) Generate daily nutrient inputs to lake (GWLF) Predict lake response (PROTECH) Status quo Scenario testing

6 Calculate daily nutrient runoff values for each scenario 1. Annual P-inputs from the farms added to annual P-input from the other land in the catchment (export coefficient) and septic tanks to produce a total annual load of P (kg y -1 ) 2. Different scenarios of possible land management were investigated (each with/without direct septic tank input) and annual P-load calculated Scenario S1 S2 S3 S4 S5 Description Status quo All farmland to deciduous forest All improved grassland to natural grassland Remove cattle; double sheep Double cattle; halve sheep 3. GWLF hydrological model (daily 12 discharge) combined with these P- loads to produce daily loads of P 10 (also using a similar approach nitrogen and silica) 8 Collect farm data Adjust for soil P deficit Add P losses from septic tank (as point or diffuse) Local weather management scenario data nutrient budget (PLANET) Calculate farm nutrientexcess excess Land cover Calculate nutrient runoff concentrations (= nutrient excess/flow) Generate daily nutrient inputs to lake (GWLF) Predict lake response (PROTECH) Generate daily runoff values Calibrate rainfall/runoff model (GWLF) Collect rainfall & flow data Status quo Scenario testing g e P (kg d -1 P ) d -1 ) P load to lake put to lake (kg timated Estimated P inp Es S1 S2 S3 S4 S5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2009

7 PROTECH models algal growth in response to: Light Heat flux Wind Nutrients Algae Collect farm data management scenario data Collect rainfall & flow data nutrient budget (PLANET) Land cover Calibrate rainfall/runoff model (GWLF) Adjust for soil P deficit Add P losses from septic tank (as point or diffuse) Local weather Calculate farm Generate daily nutrient excess runoff values Calculate nutrient runoff concentrations (= nutrient excess/flow) Generate daily nutrient inputs to lake (GWLF) Predict lake response (PROTECH) Status quo Scenario testing

8 -3 ) a (mg m - Annual mean chlo orophyll Modelled chlorophyll production vs SRP load Improved grassland to natural grassland Current conditions All farmland to deciduous forest Double cattle Halve sheep M:P No cattle Double sheep G:M H:G Phosphorus load (kg SRP y -1 )

9 Modelled cyanobacterial Chlorophyll a vs SRP load 3 ) Annual mean chlo orophyll a (mg m Phosphorus load (kg SRP y -1 )

10 What the modelling shows Despite simplifications the three models, PLANET (farm), GWLF (hydrological) and PROTECH (algal) were successfully linked to produce a reasonable simulation of fthe effect of fthe land on the lake Currently, the lake will need to improve to reach Good Ecological Status for the WFD The models suggests that if the load was halved, the lake could be brought to good ecological status (time ). The model could be used as a tool to inform future land-management decisions (has already been to some extent). Septic tanks have a relatively small effect on P and phytoplankton today, but- they can be improved without major changes to way of life and would become increasingly i important t if P-losses from the land were reduced.