8. Urban hydrology#
In this chapter, we will dive deeper into the hydrological and meteorological processes that dominate the water balance in the urban environment. In alignment with the previous chapters, we will first look at the physical processes themselves, followed by a discussion on urban hydrological metrology. Finally, we will explore modeling approaches to urban hydrology.
Nomenclature
Symbol |
Quantity |
Quantity name in Dutch |
Dimension |
Widely used unit (if not SI) |
|---|---|---|---|---|
\(A\) |
Connected area |
Aangesloten gebied |
[L\(^2\)] |
|
\(A\) |
Impervious area |
Ondoorlatend oppervlak |
[L\(^2\)] |
|
\(A_i\) |
Area of the \(i^{th}\) sub-catchment |
Oppervlakte van het \(i^{de}\) deelstroomgebied |
[L\(^2\)] |
|
\(C\) |
Groundwater seeping into the soil layer |
Grondwater dat in de bodemlaag sijpelt |
[L\(^3\)/T] |
|
\(c_{air}\) |
Celerity of sound in air |
Snelheid van geluid in lucht |
[L/T] |
|
\(C_d\) |
Calibration constant |
Kalibratieconstante |
[-] |
|
\(c_i\) |
Coefficient determining the amount of flow going through the \(i^{th}\) flux |
Coëfficiënt die bepaalt hoeveel stroom door de \(i^{de}\) flux gaat |
[-] |
|
\(c_i\) |
Runoff coefficient of the \(i^{th}\) sub-catchment |
Afvoercoëfficiënt van het \(i^{de}\) deelstroomgebied |
[-] |
|
\(c_r\) |
Runoff coefficient |
Afvoercoëfficiënt |
[-] |
|
\(d\) |
Depression storage |
Depressie-opslag |
[L] |
|
\(dS\) |
Change in stored volume |
Verandering in opgeslagen volume |
[L\(^3\)] |
|
\(dS_{sw}\) |
Change in volume stored in the drainage network |
Verandering in volume opgeslagen in het rioleringsnetwerk |
[L\(^3\)] |
|
\(dh\) |
Head of water driving the horizontal flow |
Waterdruk die de horizontale stroming aandrijft |
[L] |
|
\(dt\) |
Time interval / Modeling timestep |
Tijdsinterval / Modelleerstap |
[T] |
|
\(E_S\) |
Soil evaporation from pervious surfaces |
Bodemverdamping van doorlatende oppervlakken |
[L\(^3\)/T] |
|
\(E_T\) |
Transpiration from vegetation |
Transpiratie van vegetatie |
[L\(^3\)/T] |
|
\(E_o\) |
Free water evaporation |
Vrije waterverdamping |
[L\(^3\)/T] |
|
\(E_t\) |
Evaporation from the area |
Verdamping uit het gebied |
[L\(^3\)/T] |
|
\(g\) |
Gravitational acceleration |
Zwaartekrachtversnelling |
[L/T\(^2\)] |
|
\(h_0\) |
Length between the sensor and the invert of the pipe |
Lengte tussen de sensor en de onderkant van de pijp |
[L] |
|
\(i\) |
Rainfall for the given time period |
Neerslag in de gegeven periode |
[L/T] |
|
\(I_d\) |
Outward flux into the groundwater (exfiltration) |
Uitgaande flux naar het grondwater (exfiltratie) |
[L\(^3\)/T] |
|
\(I_e\) |
Groundwater inflow into the UDS |
Grondwaterinstroom in het UDS |
[L\(^3\)/T] |
|
\(k_1\) |
Surface type coefficient |
Oppervlaktetypecoëfficiënt |
[L] |
|
\(k\) |
Saturated hydraulic conductivity |
Verzadigde hydraulische geleidbaarheid |
[L/T] |
|
\(k(\theta)\) |
Hydraulic conductivity corresponding to the soil moisture content |
Hydraulische geleidbaarheid afhankelijk van bodemvochtgehalte |
[L/T] |
|
\(L\) |
Infiltration of water into the ground |
Infiltratie van water in de bodem |
[L\(^3\)/T] |
|
\(P\) |
Precipitation |
Neerslag |
[L\(^3\)/T] |
|
\(Q\) |
Discharge |
Afvoer |
[L\(^3\)/T] |
|
\(Q_c\) |
Wastewater production into the combined sewer |
Afvalwaterproductie in het gemengde riool |
[L\(^3\)/T] |
|
\(Q_{cso}\) |
Outward flux through the combined sewer overflow (CSO) |
Uitgaande flux via de overstort |
[L\(^3\)/T] |
|
\(Q_{cso, max}\) |
Maximum CSO rate |
Maximale overstortafvoer |
[L\(^3\)/T] |
|
\(Q_d\) |
Outward flux (influent to treatment, CSO, flooding) |
Uitgaande flux (influent naar behandeling, overstort, overstroming) |
[L\(^3\)/T] |
|
\(Q_{flood}\) |
Outward flux due to flooding |
Uitgaande flux door overstroming |
[L\(^3\)/T] |
|
\(Q_g\) |
Inward flux from the groundwater |
Instroomflux vanuit het grondwater |
[L\(^3\)/T] |
|
\(Q_i\) |
Leakage from the drinking water network |
Lekverliezen uit het drinkwaternetwerk |
[L\(^3\)/T] |
|
\(Q_{i, max}\) |
Maximum capacity of the relevant flux |
Maximale capaciteit van de betreffende flux |
[L\(^3\)/T] |
|
\(Q_{in}\) |
Inward flux to the given storage |
Instroomflux naar de gegeven opslag |
[L\(^3\)/T] |
|
\(Q_{max}\) |
Peak outflow of a catchment |
Piekafvoer van een stroomgebied |
[L\(^3\)/T] |
|
\(Q_out\) |
Outward flux from the given storage |
Uitstroomflux uit de gegeven opslag |
[L\(^3\)/T] |
|
\(Q_p\) |
Runoff from pervious areas |
Afvoer uit doorlatende gebieden |
[L\(^3\)/T] |
|
\(Q_{pump}\) |
Maximum pumping capacity |
Maximale pompcapaciteit |
[L\(^3\)/T] |
|
\(Q_s\) |
Runoff from impervious areas (roofs and roads, through gully pots and roof gullies) |
Afvoer van ondoorlatende oppervlakken (daken en wegen, via straatkolken en dakafvoeren) |
[L\(^3\)/T] |
|
\(Q_t\) |
Relevant outflow at timestep \(t\) |
Relevante uitstroom op tijdstap \(t\) |
[L\(^3\)/T] |
|
\(Q_{total,in}\) |
Sum of all inward fluxes |
Som van alle instromende fluxen |
[L\(^3\)/T] |
|
\(Q_{total,out}\) |
Sum of all outward fluxes |
Som van alle uitstromende fluxen |
[L\(^3\)/T] |
|
\(Q_{wwtp}\) |
Outward flux towards the treatment plant |
Uitgaande flux naar de waterzuiveringsinstallatie |
[L\(^3\)/T] |
|
\(q_z\) |
Hydraulic conductivity corresponding to the soil moisture content |
Verticale stroming positief voor opwaartse stroming |
[L/T] |
|
\(R\) |
Deep infiltration into the groundwater |
Diepe infiltratie in het grondwater |
[L\(^3\)/T] |
|
\(S\) |
Storage |
Opslag |
[L\(^3\)] |
|
\(s\) |
Surface slope |
Oppervlaktehelling |
[-] |
|
\(S_{s,per}\) |
Amount of water stored on the pervious surface available for infiltration |
Hoeveelheid water opgeslagen op het doorlatende oppervlak beschikbaar voor infiltratie |
[L\(^3\)] |
|
\(S_{sw}\) |
Storage volume in the UDS |
Opslagvolume in het stedelijk afwateringssysteem |
[L\(^3\)] |
|
\(S_{sw, max}\) |
Maximum storage capacity of the UDS |
Maximale opslagcapaciteit van het stedelijk afwateringssysteem |
[L\(^3\)] |
|
\(\tau\) |
Measured time between the sent and received pulse |
Gemeten tijd tussen het verzonden en ontvangen signaal |
[T] |
|
\(\theta\) |
Soil moisture content |
Bodemvochtgehalte |
[-] |
|
\(\theta_{notch}\) |
Angle of the v-notch |
Hoek van de v-kering |
[rad] |
Note
In this section, we will consider volumes [\(\mathrm{L^3}\)] expressed in mm (N.B. usually [\(\mathrm{L}\)]). This is a normalization method that allows for the inter-catchment comparison of sizes. When a sewer network, for example, has a storage capacity expressed as 10 mm, this is a volume that equates to 10 mm multiplied by the urban area (usually expressed in ha [= 10,000 m²]), leading to a volume in [\(\mathrm{L^3}\)].