Modelling flow of subterranean Pivka river in Postojnska jama, Slovenia

Abstract

IzvlečekUDK 556.32:551.44(497.471) Georg Kaufmann, Franci Gabrovšek, Janez Turk: Modeliranje toka podzemeljske Pivke v Postojnski jami, Slovenija Z avtomatskimi merilniki in registratorji podatkov smo spremljali podzemni tok Pivke v Postojnski jami na sedmih točkah med ponorom in odtočnim sifonom v Pivki jami. Podatke nivojev in pretoka smo obravnavali z modelom EPA SwMM, s katerim smo simulirali tok v poenostavljeni geometriji kanalov. S primerjavo med opazovanji in modelskimi rezultati smo določili ključne odseke (podore, zožitve, sifone, obtoke), ki najbolj vplivajo na dinamiko toka podzemne Pivke. Glavne parametre teh odsekov smo določili z inverzno metodo, ki temelji na algoritmu soseske (Neighbourhood algorithm, NA) in pri tem dobili odlično ujemanje med modelom in podatki. Ključne besede: modeliranje, hidrologija, Postojnska jama. The sub-surface flow path through the Postojnska jama cave system has been monitored with 7 stations distributed along the flow path, monitoring stage and temperature. we have used the stage data to model flow through the cave system with the program package SwMM, simulating the active parts of Postojnska jama with simplified geometry. From the comparison of stage observations and predictions, we identified key sections in the cave, which control the sub-surface flow, such as passage constrictions, sumps and by-passes. Using a formal inverse procedure, we determined the geometry of this key sections by fitting predicted to observed stages, and we achieved a very high degree of correlation.

OM-MADE: An open-source program to simulate one-dimensional solute transport in multiple exchanging conduits and storage zones

“…This model does not allow to discretize the conduits along the flow, nor to combine two exchanging advective-dispersive zones with a storage area, but it is a relevant solution to model unknown parts of the network were the main flow can divide into two conduits before merging back. To simulate more geometrically complex networks, several authors have recently proposed to use pipe flow models [Campbell and Sullivan, 2002, Peterson and Wicks, 2006, Wu et al, 2008, Chen and Goldscheider, 2014, Jeannin et al, 2015, Kaufmann et al, 2016, Vuilleumier, 2018. Using Manning-Strickler formulae and resolving Saint-Venant equations, EPA's Stormwater Management Model (SWMM, Rossman [2015]) has proved able to reproduce the turbulent flow often observed in high flowrate conditions, and can deal with variably saturated pipes.…”

“…Using Manning-Strickler formulae and resolving Saint-Venant equations, EPA's Stormwater Management Model (SWMM, Rossman [2015]) has proved able to reproduce the turbulent flow often observed in high flowrate conditions, and can deal with variably saturated pipes. It is thus used to reproduce and forecast the flow discharge at springs [e.g., Kaufmann et al, 2016, Vuilleumier, 2018, as well as to assess the impact of the con-duit and network geometries on the flow response [Peterson and Wicks, 2006]. In this approach, the network has to be explicitely represented, as well as its dimensions.…”

Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia

“…SWMM is primarily aimed to simulate flow and transport in urban sewage systems. The model has found im-portant implications in modelling karst conduit networks (Peterson & Wicks 2006;Chen & Goldscheider 2014;Kaufmann et al 2016;Gabrovšek et al 2018. SWMM solves the Saint-Venant's equations (Dingman 2015;Rossman 2015) for an arbitrary distributed network of conduits and other hydraulic elements.…”

Understanding the temporal variation of flow direction in a complex karst system (Planinska Jama, Slovenia)

“…Karst aquifers provide freshwater to about 50 % of the population of Slovenia (Turk 2010). In the Slovene Classical Karst, large springs often present an outflow from active cave systems, evolved in complex tectonic/structural settings and catchments typically characterised by mixed allogenic and autogenic recharge and networks of large conduits (Gabrovšek & Peric 2006;Gabrovšek et al 2010;Mihevc et al 2010;Turk 2010;Ravbar et al 2012;Kaufmann et al 2016). This makes their hydraulic response very variable in time: strong and pronounced flood peaks, steep recession limbs and a minimal base flow during dry periods (Ravbar 2013).…”

“…SWMM is an open-access software made primarily to simulate the propagation of flood waves through sewage networks. The model solves Saint-Venant equations for a wide variety of settings and has been successfully applied to simulate flow in conduit dominated karst systems (Campbell & Sullivan 2002;Gabrovšek & Peric 2006;Peterson & Wicks 2006;Wu et al 2008;Chen & Goldscheider 2014;Kaufmann et al 2016;Gabrovšek et al 2018).…”