4Florida Water Facts Surface Area = 170,452 km2 Average Rainfall = 140 cm (55”)Total Annual Rain = 238 billion m3 (62.6 trillion gallons)River and Stream = 51,858 milesLargest River = Apalachicola (Q = 25,000 ft3/s = 22 km3/yr)Lake Area = 12,100 km2Springs ~ 8 billion gallons/ dayGroundwater supplies 95% of water7.2 billion gallons/day; 80% to S. FloridaLow relief – travel time for water (rainfall to sea) can be decades
5The Hydrologic Check-Book Mass BalanceWater mass is conservedTherefore: Water In = Water OutSourcesRain, Snow, Groundwater, Human EffluentSinksGround, River, Atmosphere, HumansStoresWetlands, Lakes, Rivers, Soil, Aquifers
6The Water Budget (Exam 1) INFLOWOUTFLOWP= Q + ET + G + ΔSPrecipitationSurface runoffEvapotranspirationGroundwaterStorage
7Annual Water Budget - Flatwoods Transpiration(~ 70 cm)Interception(~ 30 cm)Rainfall (~ 140 cm)Surface Runoff (~ 3 cm)Infiltration to Deep Aquifer(~5 cm, though upto ~ 40 cm)Subsurface Runoff (~ 32 cm)
8Annual Water Budget – Ag Land Interception(~ 15 cm)Transpiration(~ 80 cm)Rainfall (~ 140 cm)Surface Runoff(~ 20 cm)Infiltration to Deep Aquifer(~5 cm, in areas much higher)Subsurface Runoff (~ 20 cm)
9Annual Water Budget – Urban Land Rainfall (~ 140 cm)Interception(~ 20 cm)Transpiration(~ 50 cm)Surface Runoff (~ 60 cm)Subsurface Runoff (~ 5 cm)Infiltration to Deep Aquifer(~ 2 cm)
10Changes in Internal Stores ΔStorage = Inputs – OutputsUsually easy to measure (e.g., lake volume)In > Out ?Out > in ?In = Out ?What if Inmeasured > OutmeasuredAND water level is falling?
11Rules of Water Balances Water balance terms must be in common units(usually meters depth over the watershed area).Precipitation and ET measured in depth (m/yr)Water flows measured as volumes (m3/yr).Volume = Depth x AreaDepth = Volume / Area
12Catchment Water Balance Area = 100 ha (10,000 m2 per ha)Annual Measurements:Rainfall = 2 m (tipping-bucket rain gage)Surface outflow (Q) = 2,000,000 m3 (weir)ET = 1.5 m (evaporation pan)Groundwater = 1,000,000 m3 (shallow wells)Assume ΔS=0
13Budget: P= Q + ET + G + ΔS ∆S = 0 2.0 = 0.2 + 1.5 + 0.1 + 0 (?!) Area = 100 ha; 1 ha = 10,000 m2P = 2.0 mQ = 2,000,000 m3/(100 ha * 10,000 m2/ha)= 0.2 mET = 1.5 mG = 1,000,000 m3/(100 ha * 10,000 m2/ha)= 0.1 m∆S = 02.0 = (?!)
14WatershedsA land area from which all rainfall drains to the same point.The “watershed” is technically the divide between two such areas (called basins)
15Delineating Watersheds Identify outlet pointIdentify high pointsLink high pts crossing contour lines at right-angles231
17P + Qin1 + Qin2 = Qout1 + Qout2 + ET + G1 + G1 + ΔS Why Watersheds?Control boundariesWater that falls either comes out the bottom or is abstractedImagine a water budget if you weren’t sure where the water was going…P + Qin1 + Qin2 = Qout1 + Qout2 + ET + G1 + G1 + ΔS
18Experimentation – Paired Watersheds What is the effect of forest management on:Water yieldSediment yieldNutrient exportWater temperatureTime of transport
20Paired Watershed Study of Forest Harvest Effects on Peakflows LOGGINGROAD BUILDINGBeschta et al – H.J. Andrews Experimental Forest (OR)
21Does watershed delineation work in Florida? Low-reliefDelineation of boundaries hardIn parts of Florida, water flows depend on:where it rained,where the wind is blowing andwhere people put the canals and roadsNational contour maps too coarse (5 ft)Roads act as flow delineators????
23Paired Watersheds in Florida Shown that (Riekerk 1983):High intensity logging increased water yields by 250%Low intensity logging increased water yields 150%Clear cutting altered nutrient export ratesAll forest operations (fire?) were less than urbanization (much more on this later)
24Stream Patterns Dendritic patterns follow Strahler Order 1st order is unbranched2nd order occurs when two 1st order reaches convergeIncreased order requires convergence of two reaches of the same orderWhat are springs?
25Network Forms Regional landform dictates shape Regional geology dictates drainage densityRegional climate (rainfall) dictates density and maturation rate
27Watershed Networks Mass transport is optimal at minimum work Reach and network scales at the SAME timeNecessary conditions for dendritic drainageMinimal energy expenditure at any link in the networkEqual Energy Expenditure per unit areaMinimum Energy Expenditure in the Network as a wholeRodriguez-Iturbe et al. (1992) - WRR
28Water Convergence Across Scales - St Johns River Basin- Ocklawaha River Basin- Orange Creek Sub-Basin- Newnans Lake Watershed- Hatchett Creek Watershed- ACMF “Hillslope”- Lake Mize catchmentil