Hydrologic Pathways: Precipitation, ET, Storage, Runoff & Recharge. Joe Magner, MPCA

Transcription

1 Hydrologic Pathways: Precipitation, ET, Storage, Runoff & Recharge Joe Magner, MPCA

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5 Concrete! Sluice gates Channels

6 What was the consequence Loss of 60,000 fishing jobs Initial 20 % loss of lake volume, by 1987 = 60 % of lake volume (drop = 45 feet) 5-fold > in salinity (10-45 g/l) Loss of buffered climate 10-fold > cancer + tuberculosis Polluted salt dust over large area

7 Precipitation Parameters Intensity: how fast does the precipitation fall? Duration: how long does the precipitation last? Magnitude: how much precipitation fell? Frequency (or return period): how often does it occur?

8 Storm Types Convectional storms: Short duration, small area, intense rainfall; may include hail, tornadoes. Primarily in summer, tropics, scattered. Orographic storms: On mountain barriers; downwind of lakes or coasts. Cyclonic (also Frontal or Air Mass) storms

9 Upper Midwestern Climate Cyclonic (Frontal or Air Mass) Storms: Cold Front: rain behind front, high intensity, short, small area. Warm Front: rain in advance of front, low intensity, long, large.

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12 Where Does the Precipitation Go? Terrain Landscape Slope Land Use Management 1. Storage 2. Vegetation 3. Soil/Surface Type Hydrogeologic Substrate

13 Terrain, Management, & Geology Flat Rolling Steep Row Crop Corn Herbaceous Perennial Forest Soil Geologic System 1. Lake Clay/Bedrock 2. Anoka Sand Plain 3. Des Moines Lobe Till What controls infiltration?

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15 From Brooks et al, 2003

16 Novotny & Stefan (2007) Overall upward trend in Minnesota streamflow (~1%/yr for 36 stations 1900 s thru 2002). No change in snow-melt runoff. Summer runoff increased. Higher base-flows. More higher flow days. Amplitude of change was strong after 1980.

17 Mean monthly flows for Minnesota Mankato between Q (cfs) Lenhart, Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

18 Season & Streamflow From Pat Baskfield

19 2003 April 20 May 3

20 2003 May 18 31

21 2003 June 15 28

22 Novotny & Stefan (2007) Largest changes occurred in the Minnesota River ( Stats were considerably higher in the 1990 s than any previous period.) MN River Winter low-flow rates increasing at a higher rate than any other statistic. Related to an increase in Precipitation? Between 88-02, no significant change.

23 Mid-June 2005 Beauford Hydrologic Response June 10th June 11th June 12th June 13th June 14th June 15th June 16th June 17th June 18th June 19th June 20th June 8th 6:00 No on 18 :00 June 9th Time (15-minute interval) S t r e a m f l o w ( c f s ) P r e c i p i t a t i o n ( i n c h e s ) Flow Precip From Pat Baskfield

24 June 8th 2005 Beauford Hydrologic Response Flow Precip S t r e a m f l o w ( c f s ) P r e c i p i t a t i o n ( i n c h e s ) June 8th 6:00 No on 18 :00 June 9th Time (15-minute interval) From Pat Baskfield

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26 GW Recharge & Discharge Recharge = escaped capture! Held in subsurface storage (how long?) Hydraulic Residence Time Discharge = change in residence to 1. Vegetation then transpiration or 2. Stagnant water (lake or wetland) or 3. Stream When does recharge occur?

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28 From Brooks et al, 2003

29 MN River Basin Phases of Hydrologic Change Phase 1: Clearing, plowing, ditching, normal climate (1880s-1920 s) Phase 2: Technological advances, cropping changes, drier climate (20 s-60 s) Phase 3: Maximizing field scale performance, wetter climate (60 s to current)

30 Rush & High Island Creek Watersheds Circa 1900 (After Anderson, 1998) Isolated Depressions Threshold Change

31 Southern MN Ground Moraine Infiltration, Interflow, Recharge Dense Basal Till

32 Rush & High Island Creek Watersheds Circa 1960 (After Anderson, 1998) Significant change in Hydrologic Pathway water movement.

33 Magner et al, 2004

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36 Fluid Displacement Analogy: When turning on a garden hose warmed by the sun, cold water eventually displaces warm water in the hose. Similarly, new water eventually displaces old water in a watershed. Uplands River/Stream

37 Connectivity The flow, exchange and pathways that move organisms, energy and matter through a stream system It is a continuum of hydrologic, biological, and chemical interactions To understand connectivity and manage the system, we must link multiple disciplines and data sets

38 Functional Process Zones (FPZ) (from Thorp et al., 2006) c/o US EPA

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40 USGS, 1997

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44 Questions

45 Begin your TMDL study with the End in Mind Joe Magner, Ph.D., P.H., P.S.S. Minnesota Pollution Control Agency

46 Deer Creek, Carlton, MN

47 Threshold Scale of Response

48 Fishable and Swimmable Do we know how to restore streams to meet the Clean Water Act goals? 1. Impairment is based on failure to meet water quality standards. 2. Assumed disturbance stressor. 3. What are we measuring? Surrogate = fishable & swimmable? Fishable = direct measure biological response.

49 Criteria Positioning Trade-off between forecast error (stressor) & adequacy of measuring the Designated Use (DU). Criteria close to stressor may be a poor surrogate of the DU. Criteria close to DU high degree of uncertainty forecasting the stressor.

50 Threshold Scale of Root Causes Root causes go beyond numeric criteria and look at watershed system interactions (Hydrologic Pathways and Processes). What is the critical landscape, land use, WQ condition associated with the flow regime? We don t know because too little flow data and too much epistemic uncertainty.

51 Uncertainty Epistemic uncertainty, incomplete knowledge and/or lack of sufficient data to adequately estimate. Aleatory uncertainty, inherent variability of natural systems.

52 Goal: System Restoration Is the end point WQS compliance? Is complete restoration possible? How do measure the cause-and-effect response to management actions? What is the Impaired Water Response Time to management action?

53 Eco-Stability Concepts Resistance the ability of an ecosystem to resist changes to external factors. Resilience is the ability of an ecosystem to return to normal after perturbations. (Normal is not equal to the same exact pre-disturbance condition.) (from Mitsch & Jǿrgensen, 2004)

54 Jǿrgensen s (2002) Buffer Capacity (β) β = (forcing functions)/ (state variables)

55 Forcing functions are the external variables that are driving an ecosystem.

56 State variables are internal variables intrinsic to the definition of the described ecosystem, such as lake, wetland or stream.

57 Sentinel Watershed-Systems Approach Statistically representative watershedsystems by stratifying differences in land use superimposed upon matrix of climate, geology, terrain, soils and measure system response over decades. Define natural background condition. Reduce epistemic and aleatory uncertainty

58 So What? Moves us from simple numeric thresholds to system understanding, Define logical response expectations by accounting for natural background conditions, Track system recovery with respect to implementation actions, and Reduce noise associated with climate change.

59 RLA Goal: Stratify Station Design by