Matsya Purana — Narasimha’s Victory over Hiraṇyakaśipu and the Catalogue of Apocalyptic Omens
नद्यश्च प्रतिकूलानि वहन्ति कलुषोदकाः न प्रकाशन्ति च दिशो रक्तरेणुसमाकुलाः //
nadyaśca pratikūlāni vahanti kaluṣodakāḥ na prakāśanti ca diśo raktareṇusamākulāḥ //
The rivers flow contrary to their natural course, their waters turned foul; and the directions themselves do not appear clear, being choked with red dust.
It presents classic utpāta (portents) of impending dissolution: nature reverses its order (rivers flowing against their course) and the atmosphere becomes obscured (directions hidden by red dust), signaling cosmic instability before pralaya.
Such omens imply a time for heightened vigilance and dharmic response—maintaining public order, protecting people from environmental danger, and strengthening ritual/ethical conduct rather than pursuing normal expansion or luxury, aligning with Purāṇic governance ideals during calamity.
While not giving direct Vāstu rules, it underscores an auspiciousness principle used in ritual and site-selection: environmental anomalies (turbid waters, dust-darkened horizons) are treated as inauspicious indicators, prompting postponement, purification rites, or reconsideration of timing for consecrations and constructions.