Coupling a basin erosion and river sediment transport model into a large scale hydrological model

Transcription

1 Hydrology and Geodynamics of the basins of South America 4 th scientific meeting of ORE HYBAM Lima, 6-9 September 2011 Coupling a basin erosion and river sediment transport model into a large scale hydrological model Diogo C. Buarque 1, Walter Collischonn 1, Rodrigo C.D. Paiva 1,2 1 Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. 3 Géosciences Environnement Toulouse, Université Toulouse III Paul Sabatier, Toulouse, France.

2 INTRODUCTION Understand the sediment dynamics of a river basin is of importance in analysis of land use modifications, anthropogenic pressure of economic development and climatic changes; Mathematical models can be used as tools to predict the erosion and sediment transport for different conditions; Especially useful in locals with limited data, as is generally the case of large river basins; The majority of already existent models is limited to, field scale and small basin and needs large amount of data: - Watershed Erosion Prediction Project (WEPP) - Limburg Soil Erosion Model (LISEM) - Water and Tillage Erosion Model - Sediment Delivery model (WATEM-SEDEM)

3 INTRODUCTION There is a challenge in developing a distributed model for large basin that takes into account the data limitation; Hydrology is perhaps the most important key to a better understanding of soil erosion; Coupling a reliable hydrological model with a sediment model provides a more robust tool;

4 Objective This study presents the first application and preliminary results of the large scale hydrodynamic/hydrological model MGB-IPH with a new module capable to predict basin erosion and river sediment transport in a daily time step.

5 CONTEXT HYDROLOGICAL MODELING IN THE AMAZON RIVER BASIN Interesting Challenge size of the basin (7,000,000 km 2 ); limited data; particular hydrological features: climate diversity large rivers backwater effects large wetlands Large amount of sediment 600 to 800 million tons of sediment Annually; Solimoes (62%),Madeira (35%), and originating in the Andes.

6 HYDROLOGICAL MODEL MGB - IPH (Collischonn, 2001; Paiva, 2009) Modelo de Grandes Bacias Physically/conceptual based model Daily or shorter time step Distributed Catchment based discretization HRU approach ~ 6000 catchments

7 MGB-IPH HYDROLOGICAL MODEL Water Balance ET i,j PC i EI i,j Catchment Cell i i Model grid cells Wm W i, j P i,j Dbas i,j Dsup i,j Dint i,j Qsup Qsub Qbas River channel Cell downstream catchment of cell i Downstream

8 MGB-IPH HYDROLOGICAL MODEL Flow routing modelling Muskingum Cunge and Hydrodynamic Model

9 MGB-IPH HYDROLOGICAL MODEL Hydrodynamic Model - Flood inundation model: Simple Storage model v = 0 floodplains act only as storage areas horizontal water level river floodplain lateral exchange: q fl A fl(z) dx z t z = L t = Model discretization: Catchments River reaches River cross sections Floodplain units

10 SEDIMENT MODEL TWO MODULES 1) BASIN: Prediction of erosion over the basin and sediment yield to river network; 2) RIVER: Sediment transport along the river channels. The model also uses GIS system to display relevant maps and to extract parameters from SRTM DEM with 15 resolution.

11 SEDIMENT MODEL Model Components PRE-PROCESSING SIMULATION RESULTS

12 SEDIMENT MODEL Model Components

13 SEDIMENT MODEL Model Components

14 SEDIMENT MODEL Model Components

15 SEDIMENT MODEL BASIN MODULE Erosion and sediment yield are estimated for each pixel of DEM and each HRU with the Modified Universal Soil Loss Equation (MUSLE); The sediment yield estimated from MUSLE is divided into 3 classes: silte, clay and sand, according the percentage content of this classes into each soil type. Sed 0.56 = 11.8 ( Qsurf q peak Aphru ) K C P LS2 d G Sed is the sediment yield (metric tons) Q surf is the surface runoff volume (mm H 2 O/ha) from MGB-IPH model q peak is the peak runoff rate (m 3 /s) A phru is the area of a pixel of HRU (ha) K is the soil erodibility factor (0.013 metric ton m 2 hr/(m 3 -metric ton cm)) C is the cover and management factor P is the support practice factor (P = 1 for large basins) LS 2d is a bi-dimensional topographic factor G is the factor that takes into account for possible coarse fragments.

16 SEDIMENT MODEL BASIN MODULE Peak Runoff Rate Rational Method q peak C i Aphru = i = Daily Rainfall / C = Runoff /(Daily Rainfall)

17 SEDIMENT MODEL BASIN MODULE Soil Erodibility Factor - K Erodibility means intrinsic susceptibility of soil to water erosion OPTION 1 - Provided by the user OPTION 2 - Calculated by the model with the William (1995) equation (SWAT and EPIC models) K = fcoarse _ sand f f coarse _ sand fine = f fine f org f hisand m = + s exp ms m silt m clay msilt

18 SEDIMENT MODEL BASIN MODULE Soil Erodibility Factor- K f 0.25 orgc = 1 org orgc + exp [ 2. orgc] f hisand = 1 m s m s m exp s 100 m s is the percent sand content ( mm diameter particles) m silt is the percent silt content ( mm diameter particles) m c is the percent clay content (< mm diameter particles) orgc is the percent organic carbon content of the layer (%)

19 SEDIMENT MODEL BASIN MODULE Cover and Management Factor - C Is related to the land-use and is a reduction factor to soil erosion vulnerability Provided by the user from literature Support Practice Factor - P Provided by the user Since the model applies to large basins, this parameter can be assigned as 1.0 for the entire area; Can be calculated from (Lufafa et al., 2003): P = S f where Sf is the Slope (%)

20 SEDIMENT MODEL BASIN MODULE Topographic Factor LS 2d In order to consider a two-dimensional landscape, the model determines the upslope length L from Desmet and Govers (1996) equation: L i, j ( 2 Am + D ) i, j = m+ 2 D x m i, j m+ 1 A i, m j ( 22.13) m + 1 Am = m = 0.2 m = 0.3 m = 0.4 m = 0.5 área acumulada a for for for S f 1 S f < 1 for 3 S S f f 5 < < montante do pixel 3 5 D = dx D = 2 dx

21 SEDIMENT MODEL BASIN MODULE Topographic Factor LS 2d The slope factor S is determined from Wischmeier & Smith (1978): S f 2 = sin ( θ ) sin( θ ) θ is the slope angle. Factor for Coarse Fragments G The slope factor S is determined from Wischmeier & Smith (1978): G = exp( RCK) RCK is the percent rock in the first soil layer (%).

22 SEDIMENT MODEL BASIN MODULE Sediment Delivery Routine - SDR To predict which fraction of total amount of sediment production in a catchment will reach the river channel, the model use a Sediment Delivery Ratio. Sed yeld SDR = Sed SDR = kc 1 D w kc is a calibration coefficient and D w is the weighted distance of the catchment to the river channel (m): D w n i= 1 = n W i= 1 i D Wi i i = the number of grid cells in the subbasin; Di = the flow-distance of grid cell I to the river Wi = the weight of grid cell I = 1/S f

23 SEDIMENT MODEL BASIN MODULE In large catchments only a portion of the surface runoff will reach the main channel on the day it is generated.

24 SEDIMENT MODEL RIVER MODULE Advection equation for silt and clay No erosion or deposition is allowed for silt and clay into the main channel ( AC) ( AuC + ) = t x Sediment continuity equation for sand A (1 λ) t b Q C + x q q l l = 0 ΔA b ΔA b > < deposition - erosion - - > > DEP = ΔA b EROS = ΔA Δx α b d Δx α e C t+ i+ 1 t+ 1 1 = TCi+ 1 = Transport capacity (Yang,1973)

25 SEDIMENT MODEL Transport Capacity for sand (Yang, 1973) diamiter nominal * and D (Sp) N M, : Wu and Wang (2006) 10mm d 2mm 2mm d log log 1/ 3 * log log M log log log log M log log * * * * = = < < = + = = = = = F n n s U d s s U d s N s U d s s U d s N f c f D M N d N M s s S U s US N M TC ν ω ω ω ω ν ω ω ν ω ω ν ω ω ν ω RIVER MODULE

26 FIRST APPLICATION MADEIRA RIVER BASIN Muskingum Cunge flow routing A = 1.420,00 km 2 and Q = ,00 m 3 /s 35% of the sediment amount annually transported for the Amazon river

27 DATA Precipitation and Meteorological Data Remote sensed estimates from Tropical Rainfall Measurement Mission Daily rainfall data from TRMM 3B42 algorithm Spatial resolution of 0.25 o 0.25 o Climatic Research Unit CRU for surface air temperature, atmospheric pressure, solar radiation, moisture and wind speed Digital Elevation Model HydroSHEDS - Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales (500 m resolution) Soil Type and Land Use Data A Vegetation map of South America (1 km resolution) from Eva et al. (2002) Soil maps: - SRIC (World Soil Information) / SOTERLAC (Soil and Terrain database for Latin America and Caribbean) (1: ) - Exploratory Soil Map from RADAMBRASIL (1: ) - FAO Map of World Soil Resources (1: )

28 DATA MUSLE Parameters for each Hydrological Response Unit HRU FAO Map of World Soil Resources (1: )

29 DATA Discretization Sub-Catchments flow calibration ( )

30 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

31 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

32 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

33 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

34 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

35 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

36 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

37 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

38 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

39 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

40 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

41 PRELIMINARY RESULTS BASIN MODULE Surface flow to river Sediment to river

42 PRELIMINARY RESULTS RIVER MODULE NET EROSION (sand) Difference between total amount eroded and deposited along the river.

43 PRELIMINARY RESULTS RIVER MODULE SUSPENDED SEDIMENT (silt and clay)

44 PRELIMINARY RESULTS RIVER MODULE SUSPENDED SEDIMENT Estimates from Filizola (1999)

45 PRELIMINARY RESULTS RIVER MODULE

46 PRELIMINARY RESULTS RIVER MODULE SUSPENDED SEDIMENT ORE-HYBAM 8 gauges 4 with data between

47 PRELIMINARY RESULTS RIVER MODULE PORTO VELHO Stream flow (m3/s)

48 PRELIMINARY RESULTS RIVER MODULE PORTO VELHO - Daily concentration (mg/l)

49 PRELIMINARY RESULTS RIVER MODULE RURRENABAQUE - Daily concentration (mg/l)

50 CONCLUSIONS This work is still in development; Preliminary results are promising; Peak in daily sediment could be resolve using the diffusive term into the transport equation; Mean annual values are in agreement with some field estimates; Finishing model development: - Diffusive term; - Floodplain processes (hydrodynamic or Muskingum -Cunge-Todini with floodplain); Apply the model for the whole Amazon basin; Validation using remote sensing data.

51 Hydrology and Geodynamics of the basins of South America 4 th scientific meeting of ORE HYBAM Lima, 6-9 September 2011 Obrigado Thank you Gracias Merci