Cloud-Computing Based Real-Time Flood Simulation (RealFlood Engine)

Transcription

1 Cloud-Computing Based Real-Time Flood Simulation (RealFlood Engine) Jennifer G Duan, PhD., PE Principal, KKC Engineering (UA Tech Launch) Associate Professor Delbert R. Lewis Distinguished Professor Civil Engineering and Engineering Mechanics

2 Background There is no defined drainage path in urban watershed resided in alluvial fan. Modeling surface flow over watershed needs to simulate both overland flow and channel flow. The depth of overland flow is much shallower than that of channel flow. Natural Alluvial Fan Urbanized Alluvial Fan -Reno

3 Background Santa Cruz River 2006 Flood Base Base Flow 110 cfs Flood Flow 2006 Q=37,900 cfs

4 Demands and Regulations Government requires all the buildings (residential/commercial) out of flood zone determined by hydro-models, such as CHRE2D. The flood zones are changing with development and natural changes. The model itself is always needed by water resource consulting industry. Flood insurances are needed for properties within the flood zones. Otherwise, the buildings can not be occupied by business or residence.

5 Problems in Current Practice Current practices are using several commercial models, such as Flo2D, HEC-RAS. Those models have to use special treatments to handle large watershed scaled modeling. Our model is the most robust and capable one than those. Current practices are limited by funding constrains or city/county limits, so individual project is conducted by separate companies. The approach is piece by piece, which doesn t allow the integration of projects for an entire system. Therefore, many projects failed because of negative impacts on other regions. Current practices have poor archived records, so many projects need to be re-do or repeated after several years. Current practices have minor public participation through public meetings.

6 RealFlood Innovation of Water Resource Engineering Profession RealFlood is an internet based engine that allows the real-time visualization of flood generated from each rainfall event. RealFlood runs on the state-of-art computational model, CHRE2D, a licensed software developed by Dr. Duan s research group. RealFlood aims to provide free information service to public regarding their property in case of flood event through google earth platform state-of-art computational models for water resource engineering consulting most convenient, secure, auto-archived water resource, infrastructure, emergency, and property management system to governmental agencies (local, state, federal)

7 Realflood - Capability Provide a realistic and complete flood inundation map for an entire basin (or county) directly from the precipitation Provide a simple and efficient tool for post-flood analysis using the alert gauge recorded data Enable flood forecast in real-time using NWS digital forecasted precipitation map

8 Service to Public Provide county/city planners with a complete picture of existing flood drainage system in development/undevelopment regions, which can be used to plan current urban improvement (e.g., green infrastructures) and future growth. Allow flood managers to access the modeling results through web-enabled platform to efficiently identify flooding zones, issue specific flood warnings at street level, and implement flood hazard preventive measures. Provide a calibrated and verified flood risk map to the public to raise public awareness of flood and erosion hazards of their properties.

9 CHRE2D Model (Univ of Arizona licensed) CHRE2D is a two-dimensional Hydrodynamic and Sediment transport model that simulates surface flow routing and sediment transport using numerical solutions of shallow water equations and the kinematic or diffusion wave approximation. The shallow water equations are discretized by the first-order Godunov-type finite volume method. An approximate solution to the momentum equation, kinematic or diffusion wave approximation, was introduced to overcome the difficulties in simulating very shallow overland (e.g m). The resulted CHRE2D model is capable of simulating both hydrological flow (e.g. surface flow routing) and hydraulic flow (e.g. dam break), which has not been achieved in similar commercial software, such as FLO2D, ARM2D. Additionally, the CHRE2D model implemented the Grass-type sediment transport formula to simulate the total sediment load in both overland flow and channel flow.

10 and the momentum conservation equations are: Methodology Governing Equation for Flow Simulation - Shallow water equations: mass conservation and momentum equations h ( hu) ( hv) i t x y 0 ( hu) huv ( hu gh ) ghs0x C f u u t x 2 y ( hv) huv ( hv gh ) ghs0 y C f u v t x y 2

11 SWEs in Vector Form Q F G S 0 S f S t x y h hu hv 2 2 Q hu F hu gh /2 G huv 2 2 hv huv hv gh /2 0 0 i0 S0 ghs0x S f C f u u Sr 0 ghs 0 y C 0 f v u r

12 Variable Density Flow Model The governing equations for variable density flow model is based on the two-phrase flow theory and treated sediment-laden flow density as a spatial and temporal variable. h ( hu) ( hv) S t x y ( h) ( hu) ( hv) bs t x y b ( hu) 1 2 ( huv) ( huu gh ) ghs0x C f u u t x 2 y ( hv) ( hvu) 1 2 ( hvv gh ) ghs0y C f u v t x y 2 b

13 Vector Form of Variable Density Equations Q F ( ) ( ) x Q Fy Q S0 ( U) S f ( U) Sb( U) t x y h h hu hv h hu hv U, Q Fx( Q), ( ) 2 u hu 1 Fy Q hvu huu gh v hv hvv gh huv Sb 0 0 bsb S0 ( U), S f ( U), b( ) ghs C 0x f u S U u 0 ghs 0y C 0 f v u

14 Test Case 1 Goodwin Creek Experimental Watershed The Goodwin Creek Experimental Watershed resides in the Panola County, Mississippi. As a tributary of Long Creek, it flows into the Yocona River, Yazoo River Basin. The watershed drainage area is 21.3 km 2. The watershed elevation ranges from 71 m to 128 m above the sea level. The DEM resolution used in the test is 30 m by 30 m. The rainfall event of Oct. 17, 1981, was simulated. Soil type, land use, precipitation and DEM data was based on published NRCS report.

15 Simulated Results

16 Flow Depth Flow Depth (m) Flow Depth (m) G-2 Measured SWE-KWA Time (s) G-5 Measured SWE-KWA Time (s) Flow Depth (m) Flow Depth (m) G-3 Measured SWE-KWA Time (s) G-6 Measured SWE-KWA Time (s) Flow Depth (m) Flow Depth (m) 0.1 G Measured SWE-KWA Time (s) G-7 Measured SWE-KWA Time (s)

17

18 Test Case 2: Tucson, Arizona, July 27th to Aug. 4 rd, 2006 Event Santa Cruz Basin (62 miles x 24 miles)

19 Test Case 2: Tucson, Arizona, July 27th to Aug. 4 rd, 2006 Event Rillito Basin, 60 x 40 mile

20 Test Case 2: Tucson, Arizona, July 27th to Aug. 4 rd, 2006 Event Rillito Basin, 60 x 40 mile T = 75 hrs T = 81 hrs T = 85 hrs

21 Past Event Flow Discharge and Depth

22 Past Event Street View T= 31 hrs

23 Test #3: State of Arizona Hypothetical Case: 1.0 inch precipitation over the State of Arizona for a few hours (10 hrs) T= 6 hrs

24 Test Case 3: State of Arizona Hypothetical 1 inch precipitation T = 6 hrs T = 12 hrs T = 20 hrs

25 Test Case 3: State of Arizona Phoenix Area T = 6 hrs T = 12 hrs T = 20 hrs

26 Test Case 4: 1996 Lake Ha! Ha! Catastrophic Flood Event The 1996 Lake Ha! Ha! catastrophic flood event occurred in the Saguenay region of Quebec, Canada. From July 18 to 21, 1996, an extreme precipitation event affected the Saguenay region of Quebec, Canada. At the Ha! Ha! Lake, an earthfill dyke was being overtopped by up to 0.26 m of water, and a new outlet channel formed. The failure of the dyke resulted in a peak discharge of 8 times the 100-year flood. The Ha! Ha! River was severely damaged by the resulting flood flow [Brooks and Lawrence, 1999].

27 Simulation Domain The numerical simulation started with the digital elevation model (DEM) of the Ha! Ha! River, which was surveyed in May 1994 [Capart et al., 2007]. The spatial data is based on the Modified Transverse Mercator (MTM) projection, zone 7 coordinates (NAD83). The DEM data: 275,000 < x < 282,000m on the east-west direction, 5,318,000 < y < 5,354,000 m in north-south direction. The numerical simulation started with the digital elevation model (DEM) of the Ha! Ha! River, which was surveyed in May 1994 [Capart et al., 2007]. The spatial data is based on the Modified Transverse Mercator (MTM) projection, zone 7 coordinates (NAD83).

28 Selected Cross Section Changes Bed Elevation Changes

29 Logitudinal Profile Fig 16. Measured and calculated thalwegs of test case 4: (a) 0 12 km; (b) km; (c) km. (b) (a) (c)

30 Conclusions CHRE2D model is a robust surface flow routing and sediment transport model, which is capable of simulating hydrodynamics of unsteady flow, surface flow over watershed, and sediment transport processes. The performance of the model was verified by many laboratory and field cases. For flow simulation, the model predicted accurately peak flows and flow hydrographs. The sediment module predicted reasonable changes of river cross sections and thalweg caused by a realistic dam break flow. The accuracy and simplicity of the proposed model, together with the robust implementation of well-balanced numerical scheme, makes this model suitable for practical hydraulic engineering applications. CHRE2D is licensed by the University of Arizona for Application Use.

31 Publications Duan, J. G., Bai, Y, Dominguez, F., Rivera, E., Meixner, T. (2017) Framework for incorporating climate change on flood magnitude and frequency analysis in the upper Santa Cruz River, Journal of Hydrology, 549, Yu, C. and Duan, J. G. (2017), Simulation of surface runoff using hydrodynamic model, Journal of Hydrologic Engineering, Vol. 22, No. 6, article No: , doi: /(asce)he Yu, C.S. and Duan, J.G. (2014) High Resolution Numerical Schemes for Solving Kinematic Wave Equation, Journal of Hydrology, DOI: /j.jhydrol Yu, C.S. and Duan, J.G. (2014) Two-dimensional hydrodynamic model for surface flow routing, Journal of Hydraulic Engineering, DOI: /(ASCE).HY Bai, Y. and Duan, J.G. (2014) Simulating unsteady flow and sediment transport in vegetated channel network, J. of Hydrol., Zhang, S., Duan, J. G., and Strelkoff, T. S. (2013) Gain-scale non-equilibrium sediment transport model for unsteady flow. Journal of Hydraulic Engineering, 139(1), Yu, C.S. and Duan, J.G. (2012) Two-dimensional depth-averaged unsteady turbulent flow model over obstacles, Journal of Hydraulic Research, 50:6,

32 Acknowledgement These studies are supported by funding from NSF Career Program, NSF WCS (Water and Climate Sustainability) Program, USDA Arid Land Research Center, and Pima County Government. Thank you! Questions?