Centralised Time Series Management for Continuous Hydrology on Personal Microcomputer Networks

Abstract

<p>Continuous hydrology packages such as Hydrologic Simulation Program--Fortran (HSPF) and Version 3 of the Storm Water Management Model (SWMM3) require extensive computing time even for certain cases of event modelling. In their original sequential, time-sharing, computing schemes, continuous modelling applications required a prohibitively expensive overall turn-around time and an overwhelming amount of manual Input/Output (I/O) time series (TS) data management effort. By decentralizing the processing, avoiding a time-sharing computing environment, and finding ways to keep track of I/O TS data as part of the processing, these problems can be overcome.</p> <p>Computational Hydraulics Group Time Series Manager (CHGTSM), a Database Management System (DBMS), was developed by the present author to provide easy access to TS data, independent of details of storage. CHGTSM is based on an unconventional data access technique, also developed by the author, that handles variable resolution continuous TS records. The CHG Time Series Store (CHGTSS) is prepared by the CHGTSM. CHGTSM is applied succesfully. In a case study, CHGTSM saved 88% in hard disk storage compared to the raw database. CHGTSM serves event as well as continuous modelling applications. A manual for CHGTSM is also written by the present author.</p> <p>CHGTSM can be used to distribute the database to the nodes of a linked configuration of microcomputers. Distributed processing (DISP) of centralized data is made possible by CHG Distributed Data Processing Software (CHGDPS). CHGDPS, developed by the present author, is a shell around CHGTSM which includes security provisions and node synchronization assistance. The simulation of a DISP application for continuous hydrologic modelling in a Local Area Network (LAN) improved the computing efficiency by 54% compared to sequential processing. CHGDPS will allow true concurrency only through a batch application.</p> <p>CHGDPS synchronization assistance relies on timing relations of the computational modules that are accessing the system. A program measurement (PM) technique was adopted, enhanced and applied by the present author to obtain the timing relations. Such DISP control helps the user to optimize overall system processing. For example, CHGDPS may decide (or help decide) a shift from one computational approach to another for considerations of time, space, numerical stability, and accuracy.</p> <p>The DISP scheme is flexible and can be implemented on any linked configuration of computers e.g. LAN' s, distributed data gathering and real time control (RTC) devices. The whole system, called the Computational Hydrology Work Group System (CHWGS) is assessed as an environment for continuous (or event) hydrologic modelling, distributed data gathering and distributed RTC.</p>