Unformatted text preview: GIS Applica+ons, Environmental (Scien+ﬁc) Issues, and Social Implica+ons: Rivers, Salmon, and Streamwood SAS018 GIS and Society Anne Senter PhD student of Surface Water Processes and Fluvial Geomorphology in the Hydrologic Sciences River ecosystems come in all sizes. Many CA rivers historically supported salmon popula+ons. Salmon need healthy rivers to spawn (reproduce) successfully What is streamwood? What is it good for? How much should a river have? Dichotomy between river management and ecological processes • Society uses water/rivers for many purposes – Municipal, agriculture, ﬂood control, hydropower • Ecosystems are dynamic and complex, with entwined organic and inorganic processes • Are societal uses beneﬁcial, detrimental or neutral to ecological processes? • Are ecological processes beneﬁcial, detrimental or neutral to society? Rivers are managed Streamwood is managed • What does ‘managed’ mean? • Eﬀects of river management on aqua+c ecosystems: – Dams = longitudinal disconnec+on – Diversions = less water in channel for aqua+c orgs – Channeliza+on, levees = lateral disconnec+on – Agriculture, grazing = changes to riparian corridor – Development = bridges, culverts, hard banks – Naviga+on/recrea+on = streamwood removal Salmon are managed • As a food source – What sustains salmon – popula+ons today? • Altera+ons to rivers aﬀect salmon – How? • Dams block upstream migra+on of aqua+c organisms • Dams block downstream transport of water, sediment, wood, par+culate and dissolved organic material • Regulated ﬂows alter natural hydrograph paZerns • Loss of channel complexity lowers survival • Riparian corridor altera+ons aﬀect water quality Spa+al rela+onships between streamwood and salmon redds on a regulated California river Lower Mokelumne River (LMR) below Camanche Dam Rela+ve Loca+on of Study Site Streamwood = >1m length, >10cm diameter Salmon redd = egg nests laid in gravel bedded rivers Why would we care about the spatial relationship between the two? Master’s study objec+ve: • Does the presence of streamwood inﬂuence salmon redd loca+ons? • Develop a study! – Obtain: wood loca+ons and characteris+cs – Obtain: redd loca+ons – Obtain: river habitat units • My focus: • #1 wood • #2 habitat units • #3 redds loca+ons provided by EBMUD biologists Gather ﬁeld data using Trimble GPS unit with data dic+onary In GIS, what do I need ﬁrst? Base image is a raster at 1e resolu+on Spa+al reference: GCS or PCS or both? Build habitat shapeﬁle using editor tool, create new features Define habitat shapefile categories under symbology in properties AZribute table for habitat shapeﬁle Large wood depicted as lines Wood aZribute data from Trimble GPS unit data dic+onary Redds x,y coordinates imported and shapeﬁle created How to analyze spa+al data to answer study objec+ve? • Ques+on: Does the presence of streamwood inﬂuence salmon redd loca+ons? – Determine how many redds fall within a speciﬁc distance of a wood piece (2.5, 5, and 10 m) – Iden+fy those spa+al rela+onships using GIS • Create buﬀers of varying diameter for wood and redds • Use intersect analysis tool to isolate areas of commonality – Extract intersect informa+on at diﬀerent scales • Every 25, 100, 1000 m etc. in the downstream direc+on • Per habitat unit type • Per marginal habitat versus op+mal habitat • Per unit area Divide 7.7 km reach into 25 m sec+ons 10 m buﬀers around wood and redds Intersec+on between wood and redds Used random point analysis to answer hypothesis: Ho: salmon do not build redds closer to wood in marginal habitat zones Ha: salmon do build redds closer to wood in marginal habitat zones Use Hawths tools to generate random points Results/Discussion • Ha is correct: in marginal habitats, salmon build redds closer to wood • Random tests showed signiﬁcant diﬀerences in wood‐redd interac+ons in all habitats, but par+cularly in marginal habitat • Results suggest that streamwood is an important component in river ecosystems • Recommenda+ons include addi+ons of streamwood to managed rivers to promote channel complexity Ques+ons? Streamwood addi+ons on the Lower Mokelumne River ...
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- Spring '10
- Gravel, Streamwood, salmon redds, Lower Mokelumne River, streamwood inﬂuence